linux-kernel - [PATCH 05/20] ipc/sem: Do not use ipc_rcu

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Message-Id: <20170525185107.12869-6-manfred@colorfullife.com>
Date:   Thu, 25 May 2017 20:50:52 +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 05/20] ipc/sem: 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/sem.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index 484ccf8..a04c4d6 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -258,13 +258,18 @@ static void merge_queues(struct sem_array *sma)
 	}
 }
 
+static void __sem_free(struct sem_array *sma)
+{
+	kvfree(sma);
+}
+
 static void sem_rcu_free(struct rcu_head *head)
 {
 	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
 	struct sem_array *sma = container_of(p, struct sem_array, sem_perm);
 
 	security_sem_free(sma);
-	ipc_rcu_free(head);
+	__sem_free(sma);
 }
 
 /*
@@ -482,7 +487,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
 	sma->sem_perm.security = NULL;
 	retval = security_sem_alloc(sma);
 	if (retval) {
-		ipc_rcu_putref(&sma->sem_perm, ipc_rcu_free);
+		__sem_free(sma);
 		return retval;
 	}
 
-- 
2.9.3