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From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>, edumazet@google.com
Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com,
	syzkaller@googlegroups.com, j.vosburgh@gmail.com,
	vfalico@gmail.com, andy@greyhouse.net
Subject: Re: [PATCH net] bonding/alb: properly access headers in bond_alb_xmit()
Date: Wed, 5 Feb 2020 07:16:27 -0800	[thread overview]
Message-ID: <113f8915-57bf-0a7a-1213-66ad04f80a59@gmail.com> (raw)
In-Reply-To: <20200205.143058.1599098684086589259.davem@davemloft.net>



On 2/5/20 5:30 AM, David Miller wrote:
> From: Eric Dumazet <edumazet@google.com>
> Date: Tue,  4 Feb 2020 19:26:05 -0800
> 
>> syzbot managed to send an IPX packet through bond_alb_xmit()
>> and af_packet and triggered a use-after-free.
>>
>> First, bond_alb_xmit() was using ipx_hdr() helper to reach
>> the IPX header, but ipx_hdr() was using the transport offset
>> instead of the network offset. In the particular syzbot
>> report transport offset was 0xFFFF
>>
>> This patch removes ipx_hdr() since it was only (mis)used from bonding.
>>
>> Then we need to make sure IPv4/IPv6/IPX headers are pulled
>> in skb->head before dereferencing anything.
>>
>> BUG: KASAN: use-after-free in bond_alb_xmit+0x153a/0x1590 drivers/net/bonding/bond_alb.c:1452
>> Read of size 2 at addr ffff8801ce56dfff by task syz-executor.2/18108
>>  (if (ipx_hdr(skb)->ipx_checksum != IPX_NO_CHECKSUM) ...)
>  ...
>> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>> Signed-off-by: Eric Dumazet <edumazet@google.com>
>> Reported-by: syzbot <syzkaller@googlegroups.com>
> 
> I had to read this one over a few times, but looks good.
> 
> Applied and queued up for -stable, thanks.
> 

Thanks for the scrutiny David !

      reply	other threads:[~2020-02-05 15:22 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05  3:26 [PATCH net] bonding/alb: properly access headers in bond_alb_xmit() Eric Dumazet
2020-02-05 13:30 ` David Miller
2020-02-05 15:16   ` Eric Dumazet [this message]

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