The patch titled
Subject: ipc/msg.c: avoid ipc_rcu_putref for failed ipc_addid()
has been added to the -mm tree. Its filename is
ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
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------------------------------------------------------
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: ipc/msg.c: avoid ipc_rcu_putref for failed ipc_addid()
Loosely based on a patch from Kees Cook <keescook@xxxxxxxxxxxx>:
- id and retval can be merged
- if ipc_addid() fails, then use call_rcu() directly.
The difference is that call_rcu is used for failed ipc_addid() calls, to
continue to guaranteed an rcu delay for security_msg_queue_free().
Link: http://lkml.kernel.org/r/20170525185107.12869-16-manfred@xxxxxxxxxxxxxxxx
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/msg.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff -puN ipc/msg.c~ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid ipc/msg.c
--- a/ipc/msg.c~ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid
+++ a/ipc/msg.c
@@ -132,7 +132,7 @@ static struct msg_queue *msg_alloc(void)
static int newque(struct ipc_namespace *ns, struct ipc_params *params)
{
struct msg_queue *msq;
- int id, retval;
+ int retval;
key_t key = params->key;
int msgflg = params->flg;
@@ -160,10 +160,10 @@ static int newque(struct ipc_namespace *
INIT_LIST_HEAD(&msq->q_senders);
/* ipc_addid() locks msq upon success. */
- id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
- if (id < 0) {
- ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
- return id;
+ retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
+ if (retval < 0) {
+ call_rcu(&msq->q_perm.rcu, msg_rcu_free);
+ return retval;
}
ipc_unlock_object(&msq->q_perm);
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-semc-remove-sem_base-embed-struct-sem.patch
ipc-semc-remove-sem_base-embed-struct-sem-v3.patch
ipc-merge-ipc_rcu-and-kern_ipc_perm.patch
include-linux-semh-correctly-document-sem_ctime.patch
ipc-semc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
ipc-shmc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
ipc-msgc-avoid-ipc_rcu_putref-for-failed-ipc_addid.patch
ipc-utilh-update-documentation-for-ipc_getref-and-ipc_putref.patch
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