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Date: Tue, 05 May 2015 02:16:39 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
"subashab@...eaurora.org" <subashab@...eaurora.org>,
"Eric Dumazet" <edumazet@...gle.com>
Subject: [PATCH 3.2 189/221] ping: Fix race in free in receive path
3.2.69-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: "subashab@...eaurora.org" <subashab@...eaurora.org>
[ Upstream commit fc752f1f43c1c038a2c6ae58cc739ebb5953ccb0 ]
An exception is seen in ICMP ping receive path where the skb
destructor sock_rfree() tries to access a freed socket. This happens
because ping_rcv() releases socket reference with sock_put() and this
internally frees up the socket. Later icmp_rcv() will try to free the
skb and as part of this, skb destructor is called and which leads
to a kernel panic as the socket is freed already in ping_rcv().
-->|exception
-007|sk_mem_uncharge
-007|sock_rfree
-008|skb_release_head_state
-009|skb_release_all
-009|__kfree_skb
-010|kfree_skb
-011|icmp_rcv
-012|ip_local_deliver_finish
Fix this incorrect free by cloning this skb and processing this cloned
skb instead.
This patch was suggested by Eric Dumazet
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Cc: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
net/ipv4/ping.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -717,8 +717,11 @@ void ping_rcv(struct sk_buff *skb)
sk = ping_v4_lookup(net, saddr, daddr, ntohs(icmph->un.echo.id),
skb->dev->ifindex);
if (sk != NULL) {
+ struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
+
pr_debug("rcv on socket %p\n", sk);
- ping_queue_rcv_skb(sk, skb_get(skb));
+ if (skb2)
+ ping_queue_rcv_skb(sk, skb2);
sock_put(sk);
return;
}
--
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