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authorDavidlohr Bueso <davidlohr@hp.com>2013-09-30 13:45:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-30 14:31:03 -0700
commit4271b05a227dc6175b66c3d9941aeab09048aeb2 (patch)
tree0c535ee0400940f5ad905128c9ecb405c9d65980 /kernel
parentipc/sem.c: update sem_otime for all operations (diff)
downloadlinux-dev-4271b05a227dc6175b66c3d9941aeab09048aeb2.tar.xz
linux-dev-4271b05a227dc6175b66c3d9941aeab09048aeb2.zip
ipc,msg: prevent race with rmid in msgsnd,msgrcv
This fixes a race in both msgrcv() and msgsnd() between finding the msg and actually dealing with the queue, as another thread can delete shmid underneath us if we are preempted before acquiring the kern_ipc_perm.lock. Manfred illustrates this nicely: Assume a preemptible kernel that is preempted just after msq = msq_obtain_object_check(ns, msqid) in do_msgrcv(). The only lock that is held is rcu_read_lock(). Now the other thread processes IPC_RMID. When the first task is resumed, then it will happily wait for messages on a deleted queue. Fix this by checking for if the queue has been deleted after taking the lock. Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Reported-by: Manfred Spraul <manfred@colorfullife.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: <stable@vger.kernel.org> [3.11] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
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