From f7887d40e541f74402df0684a1463c0a0bb68c68 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Mon, 6 Mar 2017 08:53:04 -0800 Subject: vrf: Fix use-after-free in vrf_xmit 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 Signed-off-by: David S. Miller --- drivers/net/vrf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/net/vrf.c') diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 22379da63400..fea687f35b5a 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -340,6 +340,7 @@ static netdev_tx_t is_ip_tx_frame(struct sk_buff *skb, struct net_device *dev) 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)) { @@ -347,7 +348,7 @@ static netdev_tx_t vrf_xmit(struct sk_buff *skb, struct net_device *dev) 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); -- cgit From 3dc857f0e8fc22610a59cbb346ba62c6e921863f Mon Sep 17 00:00:00 2001 From: David Ahern Date: Fri, 17 Mar 2017 16:07:11 -0700 Subject: net: vrf: Reset rt6i_idev in local dst after put The VRF driver takes a reference to the inet6_dev on the VRF device for its rt6_local dst when handling local traffic through the VRF device as a loopback. When the device is deleted the driver does a put on the idev but does not reset rt6i_idev in the rt6_info struct. When the dst is destroyed, dst_destroy calls ip6_dst_destroy which does a second put for what is essentially the same reference causing it to be prematurely freed. Reset rt6i_idev after the put in the vrf driver. Fixes: b4869aa2f881e ("net: vrf: ipv6 support for local traffic to local addresses") Signed-off-by: David Ahern Signed-off-by: David S. Miller --- drivers/net/vrf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/net/vrf.c') diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index fea687f35b5a..d6988db1930d 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -462,8 +462,10 @@ static void vrf_rt6_release(struct net_device *dev, struct net_vrf *vrf) } if (rt6_local) { - if (rt6_local->rt6i_idev) + if (rt6_local->rt6i_idev) { in6_dev_put(rt6_local->rt6i_idev); + rt6_local->rt6i_idev = NULL; + } dst = &rt6_local->dst; dev_put(dst->dev); -- cgit