The patch titled
Subject: ipc/util.c: correct comment in ipc_obtain_object_check
has been added to the -mm tree. Its filename is
ipc-utilc-correct-comment-in-ipc_obtain_object_check.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-utilc-correct-comment-in-ipc_obtain_object_check.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-utilc-correct-comment-in-ipc_obtain_object_check.patch
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------------------------------------------------------
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: 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/20180709151019.1336-6-manfred@xxxxxxxxxxxxxxxx
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Reviewed-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/util.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN ipc/util.c~ipc-utilc-correct-comment-in-ipc_obtain_object_check ipc/util.c
--- a/ipc/util.c~ipc-utilc-correct-comment-in-ipc_obtain_object_check
+++ a/ipc/util.c
@@ -644,8 +644,8 @@ err:
* @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.
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-reorganize-initialization-of-kern_ipc_permid.patch
ipc-reorganize-initialization-of-kern_ipc_permseq.patch
ipc-utilc-use-ipc_rcu_putref-for-failues-in-ipc_addid.patch
ipc-rename-ipcctl_pre_down_nolock.patch
ipc-utilc-correct-comment-in-ipc_obtain_object_check.patch
ipc-rename-ipc_lock-to-ipc_lock_idr.patch
ipc-utilc-further-ipc_idr_alloc-cleanups.patch
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