This is a note to let you know that I've just added the patch titled
ping: Fix race in free in receive path
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ping-fix-race-in-free-in-receive-path.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Feb 12 09:25:54 HKT 2015
From: "subashab@xxxxxxxxxxxxxx" <subashab@xxxxxxxxxxxxxx>
Date: Fri, 23 Jan 2015 22:26:02 +0000
Subject: ping: Fix race in free in receive path
From: "subashab@xxxxxxxxxxxxxx" <subashab@xxxxxxxxxxxxxx>
[ 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@xxxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/ping.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -965,8 +965,11 @@ void ping_rcv(struct sk_buff *skb)
sk = ping_lookup(net, skb, ntohs(icmph->un.echo.id));
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;
}
Patches currently in stable-queue which might be from subashab@xxxxxxxxxxxxxx are
queue-3.18/ping-fix-race-in-free-in-receive-path.patch
queue-3.18/net-rps-fix-cpu-unplug.patch
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