lkml.org 
[lkml]   [2017]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.10 35/63] vrf: Fix use-after-free in vrf_xmit
Date
4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Ahern <dsa@cumulusnetworks.com>


[ Upstream commit f7887d40e541f74402df0684a1463c0a0bb68c68 ]

KASAN detected a use-after-free:

[ 269.467067] BUG: KASAN: use-after-free in vrf_xmit+0x7f1/0x827 [vrf] at addr ffff8800350a21c0
[ 269.467067] Read of size 4 by task ssh/1879
[ 269.467067] CPU: 1 PID: 1879 Comm: ssh Not tainted 4.10.0+ #249
[ 269.467067] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 269.467067] Call Trace:
[ 269.467067] dump_stack+0x81/0xb6
[ 269.467067] kasan_object_err+0x21/0x78
[ 269.467067] kasan_report+0x2f7/0x450
[ 269.467067] ? vrf_xmit+0x7f1/0x827 [vrf]
[ 269.467067] ? ip_output+0xa4/0xdb
[ 269.467067] __asan_load4+0x6b/0x6d
[ 269.467067] vrf_xmit+0x7f1/0x827 [vrf]
...

Which corresponds to the skb access after xmit handling. Fix by saving
skb->len and using the saved value to update stats.

Fixes: 193125dbd8eb2 ("net: Introduce VRF device driver")
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/vrf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -341,6 +341,7 @@ static netdev_tx_t is_ip_tx_frame(struct

static netdev_tx_t vrf_xmit(struct sk_buff *skb, struct net_device *dev)
{
+ int len = skb->len;
netdev_tx_t ret = is_ip_tx_frame(skb, dev);

if (likely(ret == NET_XMIT_SUCCESS || ret == NET_XMIT_CN)) {
@@ -348,7 +349,7 @@ static netdev_tx_t vrf_xmit(struct sk_bu

u64_stats_update_begin(&dstats->syncp);
dstats->tx_pkts++;
- dstats->tx_bytes += skb->len;
+ dstats->tx_bytes += len;
u64_stats_update_end(&dstats->syncp);
} else {
this_cpu_inc(dev->dstats->tx_drps);

\
 
 \ /
  Last update: 2017-03-20 19:10    [W:0.304 / U:0.364 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site