From 51c23b7b7db52493d4fc869cec8c3e8fe27bfcd3 Mon Sep 17 00:00:00 2001
From: Manfred Spraul <manfred@colorfullife.com>
Date: Wed, 12 Jul 2017 14:35:19 -0700
Subject: [PATCH 15/20] ipc/msg.c: avoid ipc_rcu_putref for failed ipc_addid()
Git-commit: 51c23b7b7db52493d4fc869cec8c3e8fe27bfcd3
Patch-mainline: v4.13-rc1
References: bsc#1050323
Loosely based on a patch from Kees Cook <keescook@chromium.org>:
- 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@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
ipc/msg.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/ipc/msg.c b/ipc/msg.c
index 10094a731b8e..cd90bfde89a4 100644
--- a/ipc/msg.c
+++ b/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 *ns, struct ipc_params *params)
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);
--
2.12.0