netdev - Re: [PATCH] vrf: Fix use-after-free in vrf

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Message-Id: <20170308.231052.2021994633653740078.davem@davemloft.net>
Date:   Wed, 08 Mar 2017 23:10:52 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     dsa@...ulusnetworks.com
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH] vrf: Fix use-after-free in vrf_xmit

From: David Ahern <dsa@...ulusnetworks.com>
Date: Mon,  6 Mar 2017 08:53:04 -0800

> 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@...ulusnetworks.com>

Applied and queued up for -stable, thanks David.