linux-kernel - [PATCH 07/20] ipc/msg: Do not use ipc_rcu

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Date:   Thu, 25 May 2017 20:50:54 +0200
From:   Manfred Spraul <manfred@...orfullife.com>
To:     mtk.manpages@...il.com, Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, 1vier1@....de,
        Davidlohr Bueso <dave@...olabs.net>, mingo@...nel.org,
        peterz@...radead.org, fabf@...net.be,
        Manfred Spraul <manfred@...orfullife.com>
Subject: [PATCH 07/20] ipc/msg: Do not use ipc_rcu_free()

From: Kees Cook <keescook@...omium.org>

Avoid using ipc_rcu_free, since it just re-finds the original structure
pointer. For the pre-list-init failure path, there is no RCU needed,
since it was just allocated. It can be directly freed.

Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Manfred Spraul <manfred@...orfullife.com>
---
 ipc/msg.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index 0ed7dae..25d43e2 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -95,13 +95,18 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
 	ipc_rmid(&msg_ids(ns), &s->q_perm);
 }
 
+static void __msg_free(struct msg_queue *msq)
+{
+	kvfree(msq);
+}
+
 static void msg_rcu_free(struct rcu_head *head)
 {
 	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
 	struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
 
 	security_msg_queue_free(msq);
-	ipc_rcu_free(head);
+	__msg_free(msq);
 }
 
 /**
@@ -131,7 +136,7 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 	msq->q_perm.security = NULL;
 	retval = security_msg_queue_alloc(msq);
 	if (retval) {
-		ipc_rcu_putref(&msq->q_perm, ipc_rcu_free);
+		__msg_free(msq);
 		return retval;
 	}
 
-- 
2.9.3