From: Jakub Kicinski <kuba@kernel.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: netdev@vger.kernel.org,
syzbot+e96a7ba46281824cc46a@syzkaller.appspotmail.com,
Xin Long <lucien.xin@gmail.com>, Jon Maloy <jmaloy@redhat.com>,
Ying Xue <ying.xue@windriver.com>
Subject: Re: [Patch net] tipc: fix the skb_unshare() in tipc_buf_append()
Date: Fri, 9 Oct 2020 18:26:31 -0700 [thread overview]
Message-ID: <20201009182631.5fb4cf17@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <20201008041250.22642-1-xiyou.wangcong@gmail.com>
On Wed, 7 Oct 2020 21:12:50 -0700 Cong Wang wrote:
> skb_unshare() drops a reference count on the old skb unconditionally,
> so in the failure case, we end up freeing the skb twice here.
> And because the skb is allocated in fclone and cloned by caller
> tipc_msg_reassemble(), the consequence is actually freeing the
> original skb too, thus triggered the UAF by syzbot.
>
> Fix this by replacing this skb_unshare() with skb_cloned()+skb_copy().
>
> Fixes: ff48b6222e65 ("tipc: use skb_unshare() instead in tipc_buf_append()")
> Reported-and-tested-by: syzbot+e96a7ba46281824cc46a@syzkaller.appspotmail.com
> Cc: Xin Long <lucien.xin@gmail.com>
> Cc: Jon Maloy <jmaloy@redhat.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Applied and queued for stable, thank you!
prev parent reply other threads:[~2020-10-10 1:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 4:12 [Patch net] tipc: fix the skb_unshare() in tipc_buf_append() Cong Wang
2020-10-08 8:45 ` Xin Long
2020-10-08 17:44 ` Cong Wang
2020-10-09 3:07 ` Xin Long
2020-10-10 1:26 ` Jakub Kicinski [this message]
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