This is a note to let you know that I've just added the patch titled ipv4: Avoid crashing in ip_error to the 4.0-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: ipv4-avoid-crashing-in-ip_error.patch and it can be found in the queue-4.0 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 Sat Jun 13 09:48:35 PDT 2015 From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Date: Fri, 22 May 2015 04:58:12 -0500 Subject: ipv4: Avoid crashing in ip_error From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> [ Upstream commit 381c759d9916c42959515ad34a6d467e24a88e93 ] ip_error does not check if in_dev is NULL before dereferencing it. IThe following sequence of calls is possible: CPU A CPU B ip_rcv_finish ip_route_input_noref() ip_route_input_slow() inetdev_destroy() dst_input() With the result that a network device can be destroyed while processing an input packet. A crash was triggered with only unicast packets in flight, and forwarding enabled on the only network device. The error condition was created by the removal of the network device. As such it is likely the that error code was -EHOSTUNREACH, and the action taken by ip_error (if in_dev had been accessible) would have been to not increment any counters and to have tried and likely failed to send an icmp error as the network device is going away. Therefore handle this weird case by just dropping the packet if !in_dev. It will result in dropping the packet sooner, and will not result in an actual change of behavior. Fixes: 251da4130115b ("ipv4: Cache ip_error() routes even when not forwarding.") Reported-by: Vittorio Gambaletta <linuxbugs@xxxxxxxxxxx> Tested-by: Vittorio Gambaletta <linuxbugs@xxxxxxxxxxx> Signed-off-by: Vittorio Gambaletta <linuxbugs@xxxxxxxxxxx> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/route.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -903,6 +903,10 @@ static int ip_error(struct sk_buff *skb) bool send; int code; + /* IP on this device is disabled. */ + if (!in_dev) + goto out; + net = dev_net(rt->dst.dev); if (!IN_DEV_FORWARD(in_dev)) { switch (rt->dst.error) { Patches currently in stable-queue which might be from ebiederm@xxxxxxxxxxxx are queue-4.0/ipv4-avoid-crashing-in-ip_error.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html