On Thu, Aug 31, 2017 at 1:56 AM, idaifish <idaif...@gmail.com> wrote:
> Hi:
>    This bug seems still can be triggered by the attached PoC on latest
> Ubuntu1604 (4.4.0-94-generic)
> ============================================================================
> divide error: 0000 [#1] SMP KASAN
> Modules linked in:
> CPU: 0 PID: 14933 Comm: syz-executor0 Not tainted 4.9.45 #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> Ubuntu-1.8.2-1ubuntu1 04/01/2014
> task: ffff880076ab9900 task.stack: ffff880062ae8000
> RIP: 0010:[<ffffffff829c1df3>]  [<ffffffff829c1df3>]
> __tcp_select_window+0x2f3/0x6b0 net/ipv4/tcp_output.c:2499
>  [<ffffffff8297c36e>] tcp_cleanup_rbuf+0x43e/0x4f0 net/ipv4/tcp.c:1468
>  [<ffffffff829815df>] tcp_recvmsg+0xc2f/0x25d0 net/ipv4/tcp.c:1937

Thanks for the report. I believe this tcp_recvmsg  => tcp_cleanup_rbuf
 => __tcp_select_window divide-by-zero issue was fixed in May by Wei,

 499350a5a6e7 tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0

Looks like we should probably mark this as a -stable candidate, so
that it will eventually make it to 4.4.y, 4.9.y, 4.12.y users, etc. (I
don't see the commit in those stable branches.)


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