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

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Message-Id: <20160111.171345.1807630667848434364.davem@davemloft.net>
Date:	Mon, 11 Jan 2016 17:13:45 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	marcelo.leitner@...il.com
Cc:	netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
	dvyukov@...gle.com, vyasevich@...il.com, eric.dumazet@...il.com,
	syzkaller@...glegroups.com, kcc@...gle.com, glider@...gle.com,
	sasha.levin@...cle.com
Subject: Re: [PATCH] sctp: fix use-after-free in pr_debug statement

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.