From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: netdev@vger.kernel.org, andreyknvl@google.com
Subject: Re: [PATCH net] ip6_gre: fix ip6gre_err() invalid reads
Date: Sun, 05 Feb 2017 17:23:39 -0500 (EST) [thread overview]
Message-ID: <20170205.172339.2110599060625403300.davem@davemloft.net> (raw)
In-Reply-To: <1486279135.7793.15.camel@edumazet-glaptop3.roam.corp.google.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 04 Feb 2017 23:18:55 -0800
> From: Eric Dumazet <edumazet@google.com>
>
> Andrey Konovalov reported out of bound accesses in ip6gre_err()
>
> If GRE flags contains GRE_KEY, the following expression
> *(((__be32 *)p) + (grehlen / 4) - 1)
>
> accesses data ~40 bytes after the expected point, since
> grehlen includes the size of IPv6 headers.
>
> Let's use a "struct gre_base_hdr *greh" pointer to make this
> code more readable.
>
> p[1] becomes greh->protocol.
> grhlen is the GRE header length.
>
> Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Andrey Konovalov <andreyknvl@google.com>
So the bug is that we include offset twice in the calculation.
Applied and queued up for -stable, thanks.
prev parent reply other threads:[~2017-02-05 22:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-05 7:18 [PATCH net] ip6_gre: fix ip6gre_err() invalid reads Eric Dumazet
2017-02-05 22:23 ` David Miller [this message]
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