netdev - Re: [PATCH net] net-gro: fix use-after-free read in napi_gro

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Message-Id: <20190530.145322.336585862282292373.davem@davemloft.net>
Date:   Thu, 30 May 2019 14:53:22 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        syzkaller@...glegroups.com
Subject: Re: [PATCH net] net-gro: fix use-after-free read in
 napi_gro_frags()

From: Eric Dumazet <edumazet@...gle.com>
Date: Wed, 29 May 2019 15:36:10 -0700

> If a network driver provides to napi_gro_frags() an
> skb with a page fragment of exactly 14 bytes, the call
> to gro_pull_from_frag0() will 'consume' the fragment
> by calling skb_frag_unref(skb, 0), and the page might
> be freed and reused.
> 
> Reading eth->h_proto at the end of napi_frags_skb() might
> read mangled data, or crash under specific debugging features.
 ...
> Fixes: a50e233c50db ("net-gro: restore frag0 optimization")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>

Applied and queued up for -stable, thanks.