- Dec 01, 2021
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Alexander Mikhalitsyn authored
commit 85b6d246 upstream. Currently, the exit_shm() function not designed to work properly when task->sysvshm.shm_clist holds shm objects from different IPC namespaces. This is a real pain when sysctl kernel.shm_rmid_forced = 1, because it leads to use-after-free (reproducer exists). This is an attempt to fix the problem by extending exit_shm mechanism to handle shm's destroy from several IPC ns'es. To achieve that we do several things: 1. add a namespace (non-refcounted) pointer to the struct shmid_kernel 2. during new shm object creation (newseg()/shmget syscall) we initialize this pointer by current task IPC ns 3. exit_shm() fully reworked such that it traverses over all shp's in task->sysvshm.shm_clist and gets IPC namespace not from current task as it was before but from shp's object itself, then call shm_destroy(shp, ns). Note: We need to be really careful here, because as it was said before (1), our pointer to IPC ns non-refcnt'ed. To be on the safe side we using special helper get_ipc_ns_not_zero() which allows to get IPC ns refcounter only if IPC ns not in the "state of destruction". Q/A Q: Why can we access shp->ns memory using non-refcounted pointer? A: Because shp object lifetime is always shorther than IPC namespace lifetime, so, if we get shp object from the task->sysvshm.shm_clist while holding task_lock(task) nobody can steal our namespace. Q: Does this patch change semantics of unshare/setns/clone syscalls? A: No. It's just fixes non-covered case when process may leave IPC namespace without getting task->sysvshm.shm_clist list cleaned up. Link: https://lkml.kernel.org/r/67bb03e5-f79c-1815-e2bf-949c67047418@colorfullife.com Link: https://lkml.kernel.org/r/20211109151501.4921-1-manfred@colorfullife.com Fixes: ab602f79 ("shm: make exit_shm work proportional to task activity") Co-developed-by:
Manfred Spraul <manfred@colorfullife.com> Signed-off-by:
Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Andrei Vagin <avagin@gmail.com> Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Cc: Vasily Averin <vvs@virtuozzo.com> Cc: <stable@vger.kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- Nov 26, 2021
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Alexander Mikhalitsyn authored
commit 126e8bee upstream. Patch series "shm: shm_rmid_forced feature fixes". Some time ago I met kernel crash after CRIU restore procedure, fortunately, it was CRIU restore, so, I had dump files and could do restore many times and crash reproduced easily. After some investigation I've constructed the minimal reproducer. It was found that it's use-after-free and it happens only if sysctl kernel.shm_rmid_forced = 1. The key of the problem is that the exit_shm() function not handles shp's object destroy when task->sysvshm.shm_clist contains items from different IPC namespaces. In most cases this list will contain only items from one IPC namespace. How can this list contain object from different namespaces? The exit_shm() function is designed to clean up this list always when process leaves IPC namespace. But we made a mistake a long time ago and did not add a exit_shm() call into the setns() syscall procedures. The first idea was just to add this call to setns() syscall but it obviously changes semantics of setns() syscall and that's userspace-visible change. So, I gave up on this idea. The first real attempt to address the issue was just to omit forced destroy if we meet shp object not from current task IPC namespace [1]. But that was not the best idea because task->sysvshm.shm_clist was protected by rwsem which belongs to current task IPC namespace. It means that list corruption may occur. Second approach is just extend exit_shm() to properly handle shp's from different IPC namespaces [2]. This is really non-trivial thing, I've put a lot of effort into that but not believed that it's possible to make it fully safe, clean and clear. Thanks to the efforts of Manfred Spraul working an elegant solution was designed. Thanks a lot, Manfred! Eric also suggested the way to address the issue in ("[RFC][PATCH] shm: In shm_exit destroy all created and never attached segments") Eric's idea was to maintain a list of shm_clists one per IPC namespace, use lock-less lists. But there is some extra memory consumption-related concerns. An alternative solution which was suggested by me was implemented in ("shm: reset shm_clist on setns but omit forced shm destroy"). The idea is pretty simple, we add exit_shm() syscall to setns() but DO NOT destroy shm segments even if sysctl kernel.shm_rmid_forced = 1, we just clean up the task->sysvshm.shm_clist list. This chages semantics of setns() syscall a little bit but in comparision to the "naive" solution when we just add exit_shm() without any special exclusions this looks like a safer option. [1] https://lkml.org/lkml/2021/7/6/1108 [2] https://lkml.org/lkml/2021/7/14/736 This patch (of 2): Let's produce a warning if we trying to remove non-existing IPC object from IPC namespace kht/idr structures. This allows us to catch possible bugs when the ipc_rmid() function was called with inconsistent struct ipc_ids*, struct kern_ipc_perm* arguments. Link: https://lkml.kernel.org/r/20211027224348.611025-1-alexander.mikhalitsyn@virtuozzo.com Link: https://lkml.kernel.org/r/20211027224348.611025-2-alexander.mikhalitsyn@virtuozzo.com Co-developed-by:
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- May 26, 2021
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Varad Gautam authored
commit a11ddb37 upstream. do_mq_timedreceive calls wq_sleep with a stack local address. The sender (do_mq_timedsend) uses this address to later call pipelined_send. This leads to a very hard to trigger race where a do_mq_timedreceive call might return and leave do_mq_timedsend to rely on an invalid address, causing the following crash: RIP: 0010:wake_q_add_safe+0x13/0x60 Call Trace: __x64_sys_mq_timedsend+0x2a9/0x490 do_syscall_64+0x80/0x680 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f5928e40343 The race occurs as: 1. do_mq_timedreceive calls wq_sleep with the address of `struct ext_wait_queue` on function stack (aliased as `ewq_addr` here) - it holds a valid `struct ext_wait_queue *` as long as the stack has not been overwritten. 2. `ewq_addr` gets added to info->e_wait_q[RECV].list in wq_add, and do_mq_timedsend receives it via wq_get_first_waiter(info, RECV) to call __pipelined_op. 3. Sender calls __pipelined_op::smp_store_release(&this->state, STATE_READY). Here is where the race window begins. (`this` is `ewq_addr`.) 4. If the receiver wakes up now in do_mq_timedreceive::wq_sleep, it will see `state == STATE_READY` and break. 5. do_mq_timedreceive returns, and `ewq_addr` is no longer guaranteed to be a `struct ext_wait_queue *` since it was on do_mq_timedreceive's stack. (Although the address may not get overwritten until another function happens to touch it, which means it can persist around for an indefinite time.) 6. do_mq_timedsend::__pipelined_op() still believes `ewq_addr` is a `struct ext_wait_queue *`, and uses it to find a task_struct to pass to the wake_q_add_safe call. In the lucky case where nothing has overwritten `ewq_addr` yet, `ewq_addr->task` is the right task_struct. In the unlucky case, __pipelined_op::wake_q_add_safe gets handed a bogus address as the receiver's task_struct causing the crash. do_mq_timedsend::__pipelined_op() should not dereference `this` after setting STATE_READY, as the receiver counterpart is now free to return. Change __pipelined_op to call wake_q_add_safe on the receiver's task_struct returned by get_task_struct, instead of dereferencing `this` which sits on the receiver's stack. As Manfred pointed out, the race potentially also exists in ipc/msg.c::expunge_all and ipc/sem.c::wake_up_sem_queue_prepare. Fix those in the same way. Link: https://lkml.kernel.org/r/20210510102950.12551-1-varad.gautam@suse.com Fixes: c5b2cbdb ("ipc/mqueue.c: update/document memory barriers") Fixes: 8116b54e ("ipc/sem.c: document and update memory barriers") Fixes: 0d97a82b ("ipc/msg.c: update and document memory barriers") Signed-off-by:
Varad Gautam <varad.gautam@suse.com> Reported-by:
Matthias von Faber <matthias.vonfaber@aox-tech.de> Acked-by:
Davidlohr Bueso <dbueso@suse.de> Acked-by:
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- Sep 05, 2020
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Tobias Klauser authored
Commit 32927393 ("sysctl: pass kernel pointers to ->proc_handler") changed ctl_table.proc_handler to take a kernel pointer. Adjust the signature of proc_ipc_sem_dointvec to match ctl_table.proc_handler which fixes the following sparse error/warning: ipc/ipc_sysctl.c:94:47: warning: incorrect type in argument 3 (different address spaces) ipc/ipc_sysctl.c:94:47: expected void *buffer ipc/ipc_sysctl.c:94:47: got void [noderef] __user *buffer ipc/ipc_sysctl.c:194:35: warning: incorrect type in initializer (incompatible argument 3 (different address spaces)) ipc/ipc_sysctl.c:194:35: expected int ( [usertype] *proc_handler )( ... ) ipc/ipc_sysctl.c:194:35: got int ( * )( ... ) Fixes: 32927393 ("sysctl: pass kernel pointers to ->proc_handler") Signed-off-by:
Tobias Klauser <tklauser@distanz.ch> Signed-off-by:
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- Aug 23, 2020
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Gustavo A. R. Silva authored
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by:
Gustavo A. R. Silva <gustavoars@kernel.org>
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- Aug 12, 2020
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Liao Pingfang authored
Remove the superfuous break, as there is a 'return' before it. Signed-off-by:
Liao Pingfang <liao.pingfang@zte.com.cn> Signed-off-by:
Yi Wang <wang.yi59@zte.com.cn> Signed-off-by:
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Alexey Dobriyan authored
Two functions are only called via function pointers, don't bother inlining them. Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
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- Aug 07, 2020
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Peter Collingbourne authored
The current split between do_mmap() and do_mmap_pgoff() was introduced in commit 1fcfd8db ("mm, mpx: add "vm_flags_t vm_flags" arg to do_mmap_pgoff()") to support MPX. The wrapper function do_mmap_pgoff() always passed 0 as the value of the vm_flags argument to do_mmap(). However, MPX support has subsequently been removed from the kernel and there were no more direct callers of do_mmap(); all calls were going via do_mmap_pgoff(). Simplify the code by removing do_mmap_pgoff() and changing all callers to directly call do_mmap(), which now no longer takes a vm_flags argument. Signed-off-by:
Peter Collingbourne <pcc@google.com> Signed-off-by:
David Hildenbrand <david@redhat.com> Link: http://lkml.kernel.org/r/20200727194109.1371462-1-pcc@google.com Signed-off-by:
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- Jun 09, 2020
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Michel Lespinasse authored
This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by:
Michel Lespinasse <walken@google.com> Signed-off-by:
Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by:
Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com Signed-off-by:
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- Jun 08, 2020
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Giuseppe Scrivano authored
the reason is to avoid a delay caused by the synchronize_rcu() call in kern_umount() when the mqueue mount is freed. the code: #define _GNU_SOURCE #include <sched.h> #include <error.h> #include <errno.h> #include <stdlib.h> int main() { int i; for (i = 0; i < 1000; i++) if (unshare(CLONE_NEWIPC) < 0) error(EXIT_FAILURE, errno, "unshare"); } goes from Command being timed: "./ipc-namespace" User time (seconds): 0.00 System time (seconds): 0.06 Percent of CPU this job got: 0% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:08.05 to Command being timed: "./ipc-namespace" User time (seconds): 0.00 System time (seconds): 0.02 Percent of CPU this job got: 96% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.03 Signed-off-by:Giuseppe Scrivano <gscrivan@redhat.com> Signed-off-by:
Paul E. McKenney <paulmck@kernel.org> Reviewed-by:
Waiman Long <longman@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Link: http://lkml.kernel.org/r/20200225145419.527994-1-gscrivan@redhat.com Signed-off-by:
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Jules Irenge authored
Sparse reports a warning at freeque() warning: context imbalance in freeque() - unexpected unlock The root cause is the missing annotation at freeque() Add the missing __releases(RCU) annotation Add the missing __releases(&msq->q_perm) annotation Signed-off-by:
Jules Irenge <jbi.octave@gmail.com> Signed-off-by:
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- May 14, 2020
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Vasily Averin authored
Commit 89163f93 ("ipc/util.c: sysvipc_find_ipc() should increase position index") is causing this bug (seen on 5.6.8): # ipcs -q ------ Message Queues -------- key msqid owner perms used-bytes messages # ipcmk -Q Message queue id: 0 # ipcs -q ------ Message Queues -------- key msqid owner perms used-bytes messages 0x82db8127 0 root 644 0 0 # ipcmk -Q Message queue id: 1 # ipcs -q ------ Message Queues -------- key msqid owner perms used-bytes messages 0x82db8127 0 root 644 0 0 0x76d1fb2a 1 root 644 0 0 # ipcrm -q 0 # ipcs -q ------ Message Queues -------- key msqid owner perms used-bytes messages 0x76d1fb2a 1 root 644 0 0 0x76d1fb2a 1 root 644 0 0 # ipcmk -Q Message queue id: 2 # ipcrm -q 2 # ipcs -q ------ Message Queues -------- key msqid owner perms used-bytes messages 0x76d1fb2a 1 root 644 0 0 0x76d1fb2a 1 root 644 0 0 # ipcmk -Q Message queue id: 3 # ipcrm -q 1 # ipcs -q ------ Message Queues -------- key msqid owner perms used-bytes messages 0x7c982867 3 root 644 0 0 0x7c982867 3 root 644 0 0 0x7c982867 3 root 644 0 0 0x7c982867 3 root 644 0 0 Whenever an IPC item with a low id is deleted, the items with higher ids are duplicated, as if filling a hole. new_pos should jump through hole of unused ids, pos can be updated inside "for" cycle. Fixes: 89163f93 ("ipc/util.c: sysvipc_find_ipc() should increase position index") Reported-by:
Andreas Schwab <schwab@suse.de> Reported-by:
Randy Dunlap <rdunlap@infradead.org> Signed-off-by:
Vasily Averin <vvs@virtuozzo.com> Signed-off-by:
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- May 09, 2020
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Christian Brauner authored
Add a simple struct nsset. It holds all necessary pieces to switch to a new set of namespaces without leaving a task in a half-switched state which we will make use of in the next patch. This patch switches the existing setns logic over without causing a change in setns() behavior. This brings setns() closer to how unshare() works(). The prepare_ns() function is responsible to prepare all necessary information. This has two reasons. First it minimizes dependencies between individual namespaces, i.e. all install handler can expect that all fields are properly initialized independent in what order they are called in. Second, this makes the code easier to maintain and easier to follow if it needs to be changed. The prepare_ns() helper will only be switched over to use a flags argument in the next patch. Here it will still use nstype as a simple integer argument which was argued would be clearer. I'm not particularly opinionated about this if it really helps or not. The struct nsset itself already contains the flags field since its name already indicates that it can contain information required by different namespaces. None of this should have functional consequences. Signed-off-by:
Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by:
Serge Hallyn <serge@hallyn.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Serge Hallyn <serge@hallyn.com> Cc: Jann Horn <jannh@google.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Aleksa Sarai <cyphar@cyphar.com> Link: https://lore.kernel.org/r/20200505140432.181565-2-christian.brauner@ubuntu.com
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- May 08, 2020
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Oleg Nesterov authored
Commit cc731525 ("signal: Remove kernel interal si_code magic") changed the value of SI_FROMUSER(SI_MESGQ), this means that mq_notify() no longer works if the sender doesn't have rights to send a signal. Change __do_notify() to use do_send_sig_info() instead of kill_pid_info() to avoid check_kill_permission(). This needs the additional notify.sigev_signo != 0 check, shouldn't we change do_mq_notify() to deny sigev_signo == 0 ? Test-case: #include <signal.h> #include <mqueue.h> #include <unistd.h> #include <sys/wait.h> #include <assert.h> static int notified; static void sigh(int sig) { notified = 1; } int main(void) { signal(SIGIO, sigh); int fd = mq_open("/mq", O_RDWR|O_CREAT, 0666, NULL); assert(fd >= 0); struct sigevent se = { .sigev_notify = SIGEV_SIGNAL, .sigev_signo = SIGIO, }; assert(mq_notify(fd, &se) == 0); if (!fork()) { assert(setuid(1) == 0); mq_send(fd, "",1,0); return 0; } wait(NULL); mq_unlink("/mq"); assert(notified); return 0; } [manfred@colorfullife.com: 1) Add self_exec_id evaluation so that the implementation matches do_notify_parent 2) use PIDTYPE_TGID everywhere] Fixes: cc731525 ("signal: Remove kernel interal si_code magic") Reported-by:
Yoji <yoji.fujihar.min@gmail.com> Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Signed-off-by:
"Eric W. Biederman" <ebiederm@xmission.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Markus Elfring <elfring@users.sourceforge.net> Cc: <1vier1@web.de> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/e2a782e4-eab9-4f5c-c749-c07a8f7a4e66@colorfullife.com Signed-off-by:
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- Apr 27, 2020
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Christoph Hellwig authored
Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by:
Christoph Hellwig <hch@lst.de> Acked-by:
Andrey Ignatov <rdna@fb.com> Signed-off-by:
Al Viro <viro@zeniv.linux.org.uk>
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- Apr 10, 2020
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Vasily Averin authored
If seq_file .next function does not change position index, read after some lseek can generate unexpected output. https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by:
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- Apr 07, 2020
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Jason Yan authored
Fix the following sparse warning: ipc/shm.c:1335:6: warning: symbol 'compat_ksys_shmctl' was not declared. Should it be static? Reported-by:
Hulk Robot <hulkci@huawei.com> Signed-off-by:
Jason Yan <yanaijie@huawei.com> Signed-off-by:
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Somala Swaraj authored
Signed-off-by:
somala swaraj <somalaswaraj@gmail.com> Signed-off-by:
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Alexey Dobriyan authored
Now that "struct proc_ops" exist we can start putting there stuff which could not fly with VFS "struct file_operations"... Most of fs/proc/inode.c file is dedicated to make open/read/.../close reliable in the event of disappearing /proc entries which usually happens if module is getting removed. Files like /proc/cpuinfo which never disappear simply do not need such protection. Save 2 atomic ops, 1 allocation, 1 free per open/read/close sequence for such "permanent" files. Enable "permanent" flag for /proc/cpuinfo /proc/kmsg /proc/modules /proc/slabinfo /proc/stat /proc/sysvipc/* /proc/swaps More will come once I figure out foolproof way to prevent out module authors from marking their stuff "permanent" for performance reasons when it is not. This should help with scalability: benchmark is "read /proc/cpuinfo R times by N threads scattered over the system". N R t, s (before) t, s (after) ----------------------------------------------------- 64 4096 1.582458 1.530502 -3.2% 256 4096 6.371926 6.125168 -3.9% 1024 4096 25.64888 24.47528 -4.6% Benchmark source: #include <chrono> #include <iostream> #include <thread> #include <vector> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> const int NR_CPUS = sysconf(_SC_NPROCESSORS_ONLN); int N; const char *filename; int R; int xxx = 0; int glue(int n) { cpu_set_t m; CPU_ZERO(&m); CPU_SET(n, &m); return sched_setaffinity(0, sizeof(cpu_set_t), &m); } void f(int n) { glue(n % NR_CPUS); while (*(volatile int *)&xxx == 0) { } for (int i = 0; i < R; i++) { int fd = open(filename, O_RDONLY); char buf[4096]; ssize_t rv = read(fd, buf, sizeof(buf)); asm volatile ("" :: "g" (rv)); close(fd); } } int main(int argc, char *argv[]) { if (argc < 4) { std::cerr << "usage: " << argv[0] << ' ' << "N /proc/filename R "; return 1; } N = atoi(argv[1]); filename = argv[2]; R = atoi(argv[3]); for (int i = 0; i < NR_CPUS; i++) { if (glue(i) == 0) break; } std::vector<std::thread> T; T.reserve(N); for (int i = 0; i < N; i++) { T.emplace_back(f, i); } auto t0 = std::chrono::system_clock::now(); { *(volatile int *)&xxx = 1; for (auto& t: T) { t.join(); } } auto t1 = std::chrono::system_clock::now(); std::chrono::duration<double> dt = t1 - t0; std::cout << dt.count() << ' '; return 0; } P.S.: Explicit randomization marker is added because adding non-function pointer will silently disable structure layout randomization. [akpm@linux-foundation.org: coding style fixes] Reported-by:kbuild test robot <lkp@intel.com> Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:
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- Feb 21, 2020
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Ioanna Alifieraki authored
This reverts commit a9795584. Commit a9795584 ("ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()") removes a lock that is needed. This leads to a process looping infinitely in exit_sem() and can also lead to a crash. There is a reproducer available in [1] and with the commit reverted the issue does not reproduce anymore. Using the reproducer found in [1] is fairly easy to reach a point where one of the child processes is looping infinitely in exit_sem between for(;;) and if (semid == -1) block, while it's trying to free its last sem_undo structure which has already been freed by freeary(). Each sem_undo struct is on two lists: one per semaphore set (list_id) and one per process (list_proc). The list_id list tracks undos by semaphore set, and the list_proc by process. Undo structures are removed either by freeary() or by exit_sem(). The freeary function is invoked when the user invokes a syscall to remove a semaphore set. During this operation freeary() traverses the list_id associated with the semaphore set and removes the undo structures from both the list_id and list_proc lists. For this case, exit_sem() is called at process exit. Each process contains a struct sem_undo_list (referred to as "ulp") which contains the head for the list_proc list. When the process exits, exit_sem() traverses this list to remove each sem_undo struct. As in freeary(), whenever a sem_undo struct is removed from list_proc, it is also removed from the list_id list. Removing elements from list_id is safe for both exit_sem() and freeary() due to sem_lock(). Removing elements from list_proc is not safe; freeary() locks &un->ulp->lock when it performs list_del_rcu(&un->list_proc) but exit_sem() does not (locking was removed by commit a9795584 ("ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()"). This can result in the following situation while executing the reproducer [1] : Consider a child process in exit_sem() and the parent in freeary() (because of semctl(sid[i], NSEM, IPC_RMID)). - The list_proc for the child contains the last two undo structs A and B (the rest have been removed either by exit_sem() or freeary()). - The semid for A is 1 and semid for B is 2. - exit_sem() removes A and at the same time freeary() removes B. - Since A and B have different semid sem_lock() will acquire different locks for each process and both can proceed. The bug is that they remove A and B from the same list_proc at the same time because only freeary() acquires the ulp lock. When exit_sem() removes A it makes ulp->list_proc.next to point at B and at the same time freeary() removes B setting B->semid=-1. At the next iteration of for(;;) loop exit_sem() will try to remove B. The only way to break from for(;;) is for (&un->list_proc == &ulp->list_proc) to be true which is not. Then exit_sem() will check if B->semid=-1 which is and will continue looping in for(;;) until the memory for B is reallocated and the value at B->semid is changed. At that point, exit_sem() will crash attempting to unlink B from the lists (this can be easily triggered by running the reproducer [1] a second time). To prove this scenario instrumentation was added to keep information about each sem_undo (un) struct that is removed per process and per semaphore set (sma). CPU0 CPU1 [caller holds sem_lock(sma for A)] ... freeary() exit_sem() ... ... ... sem_lock(sma for B) spin_lock(A->ulp->lock) ... list_del_rcu(un_A->list_proc) list_del_rcu(un_B->list_proc) Undo structures A and B have different semid and sem_lock() operations proceed. However they belong to the same list_proc list and they are removed at the same time. This results into ulp->list_proc.next pointing to the address of B which is already removed. After reverting commit a9795584 ("ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()") the issue was no longer reproducible. [1] https://bugzilla.redhat.com/show_bug.cgi?id=1694779 Link: http://lkml.kernel.org/r/20191211191318.11860-1-ioanna-maria.alifieraki@canonical.com Fixes: a9795584 ("ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()") Signed-off-by:
Ioanna Alifieraki <ioanna-maria.alifieraki@canonical.com> Acked-by:
Herton R. Krzesinski <herton@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: <malat@debian.org> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jay Vosburgh <jay.vosburgh@canonical.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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- Feb 04, 2020
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Alexey Dobriyan authored
The most notable change is DEFINE_SHOW_ATTRIBUTE macro split in seq_file.h. Conversion rule is: llseek => proc_lseek unlocked_ioctl => proc_ioctl xxx => proc_xxx delete ".owner = THIS_MODULE" line [akpm@linux-foundation.org: fix drivers/isdn/capi/kcapi_proc.c] [sfr@canb.auug.org.au: fix kernel/sched/psi.c] Link: http://lkml.kernel.org/r/20200122180545.36222f50@canb.auug.org.au Link: http://lkml.kernel.org/r/20191225172546.GB13378@avx2 Signed-off-by:
Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
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Lu Shuaibing authored
A use of uninitialized memory in msgctl_down() because msqid64 in ksys_msgctl hasn't been initialized. The local | msqid64 | is created in ksys_msgctl() and then passed into msgctl_down(). Along the way msqid64 is never initialized before msgctl_down() checks msqid64->msg_qbytes. KUMSAN(KernelUninitializedMemorySantizer, a new error detection tool) reports: ================================================================== BUG: KUMSAN: use of uninitialized memory in msgctl_down+0x94/0x300 Read of size 8 at addr ffff88806bb97eb8 by task syz-executor707/2022 CPU: 0 PID: 2022 Comm: syz-executor707 Not tainted 5.2.0-rc4+ #63 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0x75/0xae __kumsan_report+0x17c/0x3e6 kumsan_report+0xe/0x20 msgctl_down+0x94/0x300 ksys_msgctl.constprop.14+0xef/0x260 do_syscall_64+0x7e/0x1f0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x4400e9 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffd869e0598 EFLAGS: 00000246 ORIG_RAX: 0000000000000047 RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004400e9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401970 R13: 0000000000401a00 R14: 0000000000000000 R15: 0000000000000000 The buggy address belongs to the page: page:ffffea0001aee5c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x100000000000000() raw: 0100000000000000 0000000000000000 ffffffff01ae0101 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kumsan: bad access detected ================================================================== Syzkaller reproducer: msgctl$IPC_RMID(0x0, 0x0) C reproducer: // autogenerated by syzkaller (https://github.com/google/syzkaller) int main(void) { syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0); syscall(__NR_msgctl, 0, 0, 0); return 0; } [natechancellor@gmail.com: adjust indentation in ksys_msgctl] Link: https://github.com/ClangBuiltLinux/linux/issues/829 Link: http://lkml.kernel.org/r/20191218032932.37479-1-natechancellor@gmail.com Link: http://lkml.kernel.org/r/20190613014044.24234-1-shuaibinglu@126.com Signed-off-by:
Lu Shuaibing <shuaibinglu@126.com> Signed-off-by:
Nathan Chancellor <natechancellor@gmail.com> Suggested-by:
Arnd Bergmann <arnd@arndb.de> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: NeilBrown <neilb@suse.com> From: Andrew Morton <akpm@linux-foundation.org> Subject: drivers/block/null_blk_main.c: fix layout Each line here overflows 80 cols by exactly one character. Delete one tab per line to fix. Cc: Shaohua Li <shli@fb.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by:
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Manfred Spraul authored
Document and update the memory barriers in ipc/sem.c: - Add smp_store_release() to wake_up_sem_queue_prepare() and document why it is needed. - Read q->status using READ_ONCE+smp_acquire__after_ctrl_dep(). as the pair for the barrier inside wake_up_sem_queue_prepare(). - Add comments to all barriers, and mention the rules in the block regarding locking. - Switch to using wake_q_add_safe(). Link: http://lkml.kernel.org/r/20191020123305.14715-6-manfred@colorfullife.com Signed-off-by:
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Manfred Spraul authored
Transfer findings from ipc/mqueue.c: - A control barrier was missing for the lockless receive case So in theory, not yet initialized data may have been copied to user space - obviously only for architectures where control barriers are not NOP. - use smp_store_release(). In theory, the refount may have been decreased to 0 already when wake_q_add() tries to get a reference. Link: http://lkml.kernel.org/r/20191020123305.14715-5-manfred@colorfullife.com Signed-off-by:
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Manfred Spraul authored
Update and document memory barriers for mqueue.c: - ewp->state is read without any locks, thus READ_ONCE is required. - add smp_aquire__after_ctrl_dep() after the READ_ONCE, we need acquire semantics if the value is STATE_READY. - use wake_q_add_safe() - document why __set_current_state() may be used: Reading task->state cannot happen before the wake_q_add() call, which happens while holding info->lock. Thus the spin_unlock() is the RELEASE, and the spin_lock() is the ACQUIRE. For completeness: there is also a 3 CPU scenario, if the to be woken up task is already on another wake_q. Then: - CPU1: spin_unlock() of the task that goes to sleep is the RELEASE - CPU2: the spin_lock() of the waker is the ACQUIRE - CPU2: smp_mb__before_atomic inside wake_q_add() is the RELEASE - CPU3: smp_mb__after_spinlock() inside try_to_wake_up() is the ACQUIRE Link: http://lkml.kernel.org/r/20191020123305.14715-4-manfred@colorfullife.com Signed-off-by:
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Davidlohr Bueso authored
pipelined_send() and pipelined_receive() are identical, so merge them. [manfred@colorfullife.com: add changelog] Link: http://lkml.kernel.org/r/20191020123305.14715-3-manfred@colorfullife.com Signed-off-by:
Davidlohr Bueso <dave@stgolabs.net> Signed-off-by:
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- Dec 09, 2019
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Pankaj Bharadiya authored
Replace all the occurrences of FIELD_SIZEOF() with sizeof_field() except at places where these are defined. Later patches will remove the unused definition of FIELD_SIZEOF(). This patch is generated using following script: EXCLUDE_FILES="include/linux/stddef.h|include/linux/kernel.h" git grep -l -e "\bFIELD_SIZEOF\b" | while read file; do if [[ "$file" =~ $EXCLUDE_FILES ]]; then continue fi sed -i -e 's/\bFIELD_SIZEOF\b/sizeof_field/g' $file; done Signed-off-by:
Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com> Link: https://lore.kernel.org/r/20190924105839.110713-3-pankaj.laxminarayan.bharadiya@intel.com Co-developed-by:
Kees Cook <keescook@chromium.org> Signed-off-by:
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- Nov 15, 2019
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Arnd Bergmann authored
The CONFIG_64BIT_TIME option is defined on all architectures, and can be removed for simplicity now. Signed-off-by:
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- Sep 26, 2019
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Joel Fernandes (Google) authored
CONFIG_PROVE_RCU_LIST requires list_for_each_entry_rcu() to pass a lockdep expression if using srcu or locking for protection. It can only check regular RCU protection, all other protection needs to be passed as lockdep expression. Link: http://lkml.kernel.org/r/20190830231817.76862-2-joel@joelfernandes.org Signed-off-by:
Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Jonathan Derrick <jonathan.derrick@intel.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by:
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Markus Elfring authored
Null pointers were assigned to local variables in a few cases as exception handling. The jump target “out” was used where no meaningful data processing actions should eventually be performed by branches of an if statement then. Use an additional jump target for calling dev_kfree_skb() directly. Return also directly after error conditions were detected when no extra clean-up is needed by this function implementation. Link: http://lkml.kernel.org/r/592ef10e-0b69-72d0-9789-fc48f638fdfd@web.de Signed-off-by:
Markus Elfring <elfring@users.sourceforge.net> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by:
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Markus Elfring authored
dev_kfree_skb() input parameter validation, thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Link: http://lkml.kernel.org/r/07477187-63e5-cc80-34c1-32dd16b38e12@web.de Signed-off-by:
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- Sep 07, 2019
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Arnd Bergmann authored
Matt bisected a sparc64 specific issue with semctl, shmctl and msgctl to a commit from my y2038 series in linux-5.1, as I missed the custom sys_ipc() wrapper that sparc64 uses in place of the generic version that I patched. The problem is that the sys_{sem,shm,msg}ctl() functions in the kernel now do not allow being called with the IPC_64 flag any more, resulting in a -EINVAL error when they don't recognize the command. Instead, the correct way to do this now is to call the internal ksys_old_{sem,shm,msg}ctl() functions to select the API version. As we generally move towards these functions anyway, change all of sparc_ipc() to consistently use those in place of the sys_*() versions, and move the required ksys_*() declarations into linux/syscalls.h The IS_ENABLED(CONFIG_SYSVIPC) check is required to avoid link errors when ipc is disabled. Reported-by:Matt Turner <mattst88@gmail.com> Fixes: 275f2214 ("ipc: rename old-style shmctl/semctl/msgctl syscalls") Cc: stable@vger.kernel.org Tested-by:
Anatoly Pugachev <matorola@gmail.com> Signed-off-by:
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- Sep 05, 2019
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Al Viro authored
For vfs_get_keyed_super users. Signed-off-by:
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- Jul 19, 2019
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Matteo Croce authored
In the sysctl code the proc_dointvec_minmax() function is often used to validate the user supplied value between an allowed range. This function uses the extra1 and extra2 members from struct ctl_table as minimum and maximum allowed value. On sysctl handler declaration, in every source file there are some readonly variables containing just an integer which address is assigned to the extra1 and extra2 members, so the sysctl range is enforced. The special values 0, 1 and INT_MAX are very often used as range boundary, leading duplication of variables like zero=0, one=1, int_max=INT_MAX in different source files: $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l 248 Add a const int array containing the most commonly used values, some macros to refer more easily to the correct array member, and use them instead of creating a local one for every object file. This is the bloat-o-meter output comparing the old and new binary compiled with the default Fedora config: # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164) Data old new delta sysctl_vals - 12 +12 __kstrtab_sysctl_vals - 12 +12 max 14 10 -4 int_max 16 - -16 one 68 - -68 zero 128 28 -100 Total: Before=20583249, After=20583085, chg -0.00% [mcroce@redhat.com: tipc: remove two unused variables] Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com [akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c] [arnd@arndb.de: proc/sysctl: make firmware loader table conditional] Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de [akpm@linux-foundation.org: fix fs/eventpoll.c] Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com Signed-off-by:Matteo Croce <mcroce@redhat.com> Signed-off-by:
Aaron Tomlin <atomlin@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
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- Jul 17, 2019
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Kees Cook authored
Andreas Christoforou reported: UBSAN: Undefined behaviour in ipc/mqueue.c:414:49 signed integer overflow: 9 * 2305843009213693951 cannot be represented in type 'long int' ... Call Trace: mqueue_evict_inode+0x8e7/0xa10 ipc/mqueue.c:414 evict+0x472/0x8c0 fs/inode.c:558 iput_final fs/inode.c:1547 [inline] iput+0x51d/0x8c0 fs/inode.c:1573 mqueue_get_inode+0x8eb/0x1070 ipc/mqueue.c:320 mqueue_create_attr+0x198/0x440 ipc/mqueue.c:459 vfs_mkobj+0x39e/0x580 fs/namei.c:2892 prepare_open ipc/mqueue.c:731 [inline] do_mq_open+0x6da/0x8e0 ipc/mqueue.c:771 Which could be triggered by: struct mq_attr attr = { .mq_flags = 0, .mq_maxmsg = 9, .mq_msgsize = 0x1fffffffffffffff, .mq_curmsgs = 0, }; if (mq_open("/testing", 0x40, 3, &attr) == (mqd_t) -1) perror("mq_open"); mqueue_get_inode() was correctly rejecting the giant mq_msgsize, and preparing to return -EINVAL. During the cleanup, it calls mqueue_evict_inode() which performed resource usage tracking math for updating "user", before checking if there was a valid "user" at all (which would indicate that the calculations would be sane). Instead, delay this check to after seeing a valid "user". The overflow was real, but the results went unused, so while the flaw is harmless, it's noisy for kernel fuzzers, so just fix it by moving the calculation under the non-NULL "user" where it actually gets used. Link: http://lkml.kernel.org/r/201906072207.ECB65450@keescook Signed-off-by:Andreas Christoforou <andreaschristofo@gmail.com> Acked-by:
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- Jun 05, 2019
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Thomas Gleixner authored
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation version 2 of the license extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 315 file(s). Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Reviewed-by:
Allison Randal <allison@lohutok.net> Reviewed-by:
Armijn Hemel <armijn@tjaldur.nl> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de Signed-off-by:
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- May 25, 2019
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Al Viro authored
... so that we could lift the capability checks into ->get_tree() caller Signed-off-by:
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- May 24, 2019
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Thomas Gleixner authored
Based on 1 normalized pattern(s): this file is released under gnu general public licence version 2 or at your option any later version see the file copying for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1 file(s). Signed-off-by:
Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by:
Richard Fontana <rfontana@redhat.com> Reviewed-by:
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- May 15, 2019
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Manfred Spraul authored
For ipcmni_extend mode, the sequence number space is only 7 bits. So the chance of id reuse is relatively high compared with the non-extended mode. To alleviate this id reuse problem, this patch enables cyclic allocation for the index to the radix tree (idx). The disadvantage is that this can cause a slight slow-down of the fast path, as the radix tree could be higher than necessary. To limit the radix tree height, I have chosen the following limits: 1) The cycling is done over in_use*1.5. 2) At least, the cycling is done over "normal" ipcnmi mode: RADIX_TREE_MAP_SIZE elements "ipcmni_extended": 4096 elements Result: - for normal mode: No change for <= 42 active ipc elements. With more than 42 active ipc elements, a 2nd level would be added to the radix tree. Without cyclic allocation, a 2nd level would be added only with more than 63 active elements. - for extended mode: Cycling creates always at least a 2-level radix tree. With more than 2730 active objects, a 3rd level would be added, instead of > 4095 active objects until the 3rd level is added without cyclic allocation. For a 2-level radix tree compared to a 1-level radix tree, I have observed < 1% performance impact. Notes: 1) Normal "x=semget();y=semget();" is unaffected: Then the idx is e.g. a and a+1, regardless if idr_alloc() or idr_alloc_cyclic() is used. 2) The -1% happens in a microbenchmark after this situation: x=semget(); for(i=0;i<4000;i++) {t=semget();semctl(t,0,IPC_RMID);} y=semget(); Now perform semget calls on x and y that do not sleep. 3) The worst-case reuse cycle time is unfortunately unaffected: If you have 2^24-1 ipc objects allocated, and get/remove the last possible element in a loop, then the id is reused after 128 get/remove pairs. Performance check: A microbenchmark that performes no-op semop() randomly on two IDs, with only these two IDs allocated. The IDs were set using /proc/sys/kernel/sem_next_id. The test was run 5 times, averages are shown. 1 & 2: Base (6.22 seconds for 10.000.000 semops) 1 & 40: -0.2% 1 & 3348: - 0.8% 1 & 27348: - 1.6% 1 & 15777204: - 3.2% Or: ~12.6 cpu cycles per additional radix tree level. The cpu is an Intel I3-5010U. ~1300 cpu cycles/syscall is slower than what I remember (spectre impact?). V2 of the patch: - use "min" and "max" - use RADIX_TREE_MAP_SIZE * RADIX_TREE_MAP_SIZE instead of (2<<12). [akpm@linux-foundation.org: fix max() warning] Link: http://lkml.kernel.org/r/20190329204930.21620-3-longman@redhat.com Signed-off-by: -
Manfred Spraul authored
Rewrite, based on the patch from Waiman Long: The mixing in of a sequence number into the IPC IDs is probably to avoid ID reuse in userspace as much as possible. With ipcmni_extend mode, the number of usable sequence numbers is greatly reduced leading to higher chance of ID reuse. To address this issue, we need to conserve the sequence number space as much as possible. Right now, the sequence number is incremented for every new ID created. In reality, we only need to increment the sequence number when new allocated ID is not greater than the last one allocated. It is in such case that the new ID may collide with an existing one. This is being done irrespective of the ipcmni mode. In order to avoid any races, the index is first allocated and then the pointer is replaced. Changes compared to the initial patch: - Handle failures from idr_alloc(). - Avoid that concurrent operations can see the wrong sequence number. (This is achieved by using idr_replace()). - IPCMNI_SEQ_SHIFT is not a constant, thus renamed to ipcmni_seq_shift(). - IPCMNI_SEQ_MAX is not a constant, thus renamed to ipcmni_seq_max(). Link: http://lkml.kernel.org/r/20190329204930.21620-2-longman@redhat.com Signed-off-by:
Matthew Wilcox <willy@infradead.org> Acked-by:
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