Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 48/50] ipc/sem.c: synchronize the proc interface | Date | Wed, 16 Oct 2013 10:45:34 -0700 |
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3.11-stable review patch. If anyone has any objections, please let me know.
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From: Manfred Spraul <manfred@colorfullife.com>
commit d8c633766ad88527f25d9f81a5c2f083d78a2b39 upstream.
The proc interface is not aware of sem_lock(), it instead calls ipc_lock_object() directly. This means that simple semop() operations can run in parallel with the proc interface. Right now, this is uncritical, because the implementation doesn't do anything that requires a proper synchronization.
But it is dangerous and therefore should be fixed.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Rik van Riel <riel@redhat.com> 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>
--- ipc/sem.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/ipc/sem.c +++ b/ipc/sem.c @@ -2103,6 +2103,14 @@ static int sysvipc_sem_proc_show(struct struct sem_array *sma = it; time_t sem_otime; + /* + * The proc interface isn't aware of sem_lock(), it calls + * ipc_lock_object() directly (in sysvipc_find_ipc). + * In order to stay compatible with sem_lock(), we must wait until + * all simple semop() calls have left their critical regions. + */ + sem_wait_array(sma); + sem_otime = get_semotime(sma); return seq_printf(s,
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