netdev - Re: [PATCH net] sctp: kfree

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Message-Id: <20181203.155516.1922731498178619066.davem@davemloft.net>
Date:   Mon, 03 Dec 2018 15:55:16 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     lucien.xin@...il.com
Cc:     netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
        marcelo.leitner@...il.com, nhorman@...driver.com
Subject: Re: [PATCH net] sctp: kfree_rcu asoc

From: Xin Long <lucien.xin@...il.com>
Date: Sat,  1 Dec 2018 01:36:59 +0800

> In sctp_hash_transport/sctp_epaddr_lookup_transport, it dereferences
> a transport's asoc under rcu_read_lock while asoc is freed not after
> a grace period, which leads to a use-after-free panic.
> 
> This patch fixes it by calling kfree_rcu to make asoc be freed after
> a grace period.
> 
> Note that only the asoc's memory is delayed to free in the patch, it
> won't cause sk to linger longer.
> 
> Thanks Neil and Marcelo to make this clear.
> 
> Fixes: 7fda702f9315 ("sctp: use new rhlist interface on sctp transport rhashtable")
> Fixes: cd2b70875058 ("sctp: check duplicate node before inserting a new transport")
> Reported-by: syzbot+0b05d8aa7cb185107483@...kaller.appspotmail.com
> Reported-by: syzbot+aad231d51b1923158444@...kaller.appspotmail.com
> Suggested-by: Neil Horman <nhorman@...driver.com>
> Signed-off-by: Xin Long <lucien.xin@...il.com>

Applied and queued up for -stable, thanks.