netdev - Re: [PATCH] sctp: fix use-after-free in pr

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Message-ID: <CACT4Y+Z+f4DQRQo0zuH8+7q799dJuGFtjmak7tOMx_TWdrX3Kw@mail.gmail.com>
Date:	Tue, 12 Jan 2016 09:41:18 +0100
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	David Miller <davem@...emloft.net>
Cc:	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
	netdev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
	Vladislav Yasevich <vyasevich@...il.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: [PATCH] sctp: fix use-after-free in pr_debug statement

On Mon, Jan 11, 2016 at 11:13 PM, David Miller <davem@...emloft.net> wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
> Date: Fri,  8 Jan 2016 11:00:54 -0200
>
>> Dmitry Vyukov reported a use-after-free in the code expanded by the
>> macro debug_post_sfx, which is caused by the use of the asoc pointer
>> after it was freed within sctp_side_effect() scope.
>>
>> This patch fixes it by allowing sctp_side_effect to clear that asoc
>> pointer when the TCB is freed.
>>
>> As Vlad explained, we also have to cover the SCTP_DISPOSITION_ABORT case
>> because it will trigger DELETE_TCB too on that same loop.
>>
>> Also, there were places issuing SCTP_CMD_INIT_FAILED and ASSOC_FAILED
>> but returning SCTP_DISPOSITION_CONSUME, which would fool the scheme
>> above. Fix it by returning SCTP_DISPOSITION_ABORT instead.
>>
>> The macro is already prepared to handle such NULL pointer.
>>
>> Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
>> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
>
> Applied, thank you.


Tested with this patch for half a day. I did not see any reports
related to pr_debug. Let's consider this as fixed.
Thanks!