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Message-Id: <20151207144921.085257915@linuxfoundation.org>
Date: Mon, 7 Dec 2015 09:55:19 -0500
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Greg Thelen <gthelen@...gle.com>,
Eric Dumazet <edumazet@...gle.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.2 029/124] net: fix a race in dst_release()
4.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@...gle.com>
[ Upstream commit d69bbf88c8d0b367cf3e3a052f6daadf630ee566 ]
Only cpu seeing dst refcount going to 0 can safely
dereference dst->flags.
Otherwise an other cpu might already have freed the dst.
Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst")
Reported-by: Greg Thelen <gthelen@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/core/dst.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -287,7 +287,7 @@ void dst_release(struct dst_entry *dst)
if (unlikely(newrefcnt < 0))
net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
__func__, dst, newrefcnt);
- if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt)
+ if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE))
call_rcu(&dst->rcu_head, dst_destroy_rcu);
}
}
--
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