This is a note to let you know that I've just added the patch titled
net: loopback: fix a dst refcounting issue
to the 3.4-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:
net-loopback-fix-a-dst-refcounting-issue.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From d812dc02280cea5f7c49cefdc2b1ebfd3ba7e48d Mon Sep 17 00:00:00 2001
From: Eric Dumazet <[email protected]>
Date: Fri, 25 Jan 2013 07:44:41 +0000
Subject: net: loopback: fix a dst refcounting issue
From: Eric Dumazet <[email protected]>
[ Upstream commit 794ed393b707f01858f5ebe2ae5eabaf89d00022 ]
Ben Greear reported crashes in ip_rcv_finish() on a stress
test involving many macvlans.
We tracked the bug to a dst use after free. ip_rcv_finish()
was calling dst->input() and got garbage for dst->input value.
It appears the bug is in loopback driver, lacking
a skb_dst_force() before calling netif_rx().
As a result, a non refcounted dst, normally protected by a
RCU read_lock section, was escaping this section and could
be freed before the packet being processed.
[<ffffffff813a3c4d>] loopback_xmit+0x64/0x83
[<ffffffff81477364>] dev_hard_start_xmit+0x26c/0x35e
[<ffffffff8147771a>] dev_queue_xmit+0x2c4/0x37c
[<ffffffff81477456>] ? dev_hard_start_xmit+0x35e/0x35e
[<ffffffff8148cfa6>] ? eth_header+0x28/0xb6
[<ffffffff81480f09>] neigh_resolve_output+0x176/0x1a7
[<ffffffff814ad835>] ip_finish_output2+0x297/0x30d
[<ffffffff814ad6d5>] ? ip_finish_output2+0x137/0x30d
[<ffffffff814ad90e>] ip_finish_output+0x63/0x68
[<ffffffff814ae412>] ip_output+0x61/0x67
[<ffffffff814ab904>] dst_output+0x17/0x1b
[<ffffffff814adb6d>] ip_local_out+0x1e/0x23
[<ffffffff814ae1c4>] ip_queue_xmit+0x315/0x353
[<ffffffff814adeaf>] ? ip_send_unicast_reply+0x2cc/0x2cc
[<ffffffff814c018f>] tcp_transmit_skb+0x7ca/0x80b
[<ffffffff814c3571>] tcp_connect+0x53c/0x587
[<ffffffff810c2f0c>] ? getnstimeofday+0x44/0x7d
[<ffffffff810c2f56>] ? ktime_get_real+0x11/0x3e
[<ffffffff814c6f9b>] tcp_v4_connect+0x3c2/0x431
[<ffffffff814d6913>] __inet_stream_connect+0x84/0x287
[<ffffffff814d6b38>] ? inet_stream_connect+0x22/0x49
[<ffffffff8108d695>] ? _local_bh_enable_ip+0x84/0x9f
[<ffffffff8108d6c8>] ? local_bh_enable+0xd/0x11
[<ffffffff8146763c>] ? lock_sock_nested+0x6e/0x79
[<ffffffff814d6b38>] ? inet_stream_connect+0x22/0x49
[<ffffffff814d6b49>] inet_stream_connect+0x33/0x49
[<ffffffff814632c6>] sys_connect+0x75/0x98
This bug was introduced in linux-2.6.35, in commit
7fee226ad2397b (net: add a noref bit on skb dst)
skb_dst_force() is enforced in dev_queue_xmit() for devices having a
qdisc.
Reported-by: Ben Greear <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Tested-by: Ben Greear <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/net/loopback.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -77,6 +77,11 @@ static netdev_tx_t loopback_xmit(struct
skb_orphan(skb);
+ /* Before queueing this packet to netif_rx(),
+ * make sure dst is refcounted.
+ */
+ skb_dst_force(skb);
+
skb->protocol = eth_type_trans(skb, dev);
/* it's OK to use per_cpu_ptr() because BHs are off */
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/tcp-frto-should-not-set-snd_cwnd-to-0.patch
queue-3.4/tcp-fix-for-zero-packets_in_flight-was-too-broad.patch
queue-3.4/net-prevent-setting-ttl-0-via-ip_ttl.patch
queue-3.4/netxen-fix-off-by-one-bug-in-netxen_release_tx_buffer.patch
queue-3.4/net-loopback-fix-a-dst-refcounting-issue.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
