Commit 2e5ceb45 authored Aug 21, 2018 by Manfred Spraul Committed by Linus Torvalds Aug 22, 2018

ipc/util.c: correct comment in ipc_obtain_object_check

The comment that explains ipc_obtain_object_check is wrong: The function
checks the sequence number, not the reference counter.

Note that checking the reference counter would be meaningless: The
reference counter is decreased without holding any locks, thus an object
with kern_ipc_perm.deleted=true may disappear at the end of the next rcu
grace period.

Link: http://lkml.kernel.org/r/20180712185241.4017-6-manfred@colorfullife.com


Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4241c1a3

ipc/util.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -629,8 +629,8 @@ struct kern_ipc_perm ipc_lock(struct ipc_ids ids, int id)
		* @ids: ipc identifier set
		* @id: ipc id to look for
		*
		* Similar to ipc_obtain_object_idr() but also checks
		* the ipc object reference counter.
		* Similar to ipc_obtain_object_idr() but also checks the ipc object
		* sequence number.
		*
		* Call inside the RCU critical section.
		* The ipc object is not locked on exit.