netdev - Re: [PATH net] ipv4: keep skb->dst around in presence of IP options

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Date:   Sat, 04 Feb 2017 19:43:02 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     eric.dumazet@...il.com
Cc:     netdev@...r.kernel.org, andreyknvl@...gle.com, dvyukov@...gle.com
Subject: Re: [PATH net] ipv4: keep skb->dst around in presence of IP options

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Sat, 04 Feb 2017 11:16:52 -0800

> From: Eric Dumazet <edumazet@...gle.com>
> 
> Andrey Konovalov got crashes in __ip_options_echo() when a NULL skb->dst
> is accessed.
> 
> ipv4_pktinfo_prepare() should not drop the dst if (evil) IP options
> are present.
> 
> We could refine the test to the presence of ts_needtime or srr,
> but IP options are not often used, so let's be conservative.
> 
> Thanks to syzkaller team for finding this bug.
> 
> Fixes: d826eb14ecef ("ipv4: PKTINFO doesnt need dst reference")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Andrey Konovalov <andreyknvl@...gle.com>

Applied and queued up for -stable, thanks.