Messages in this thread | | | Subject | Re: [PATCH] [ipc/sem.c] fix race with concurrent semtimedop() timeouts and IPC_RMID | From | Eric Dumazet <> | Date | Thu, 21 Jul 2011 10:12:11 +0200 |
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Le mercredi 20 juillet 2011 à 23:58 -0700, Andrew Morton a écrit : > On Thu, 21 Jul 2011 08:42:53 +0200 Manfred Spraul <manfred@colorfullife.com> wrote: > > > If a semaphore array is removed and in parallel a sleeping task is woken up > > (signal or timeout, does not matter), then the woken up task does not wait > > until wake_up_sem_queue_do() is completed. This will cause crashes, because > > wake_up_sem_queue_do() will read from a stale pointer. > > > > The fix is simple: Regardless of anything, always call get_queue_result(). > > This function waits until wake_up_sem_queue_do() has finished it's task. > > > > Andrew, could you please take care of merging the patch? > > yup, thanks for this. It's good to hear from you, and that you've > still got what it takes :) > > Do you know how long this bug has been around for? Somewhere between > 2.6.32 and 2.6.36, but that a large interval!
As I said, bug was introduced in commit 0a2b9d4c79671b05956806ede5d054e03ae56280 (ipc/sem.c: move wake_up_process out of the spinlock section)
(so first faulty kernel version is 2.6.35)
Please also add this bugzilla reference :
https://bugzilla.kernel.org/show_bug.cgi?id=27142
Reported-by: Harald Laabs <kernelml@dasr.de> Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
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