On 03/11/2019 11:41 AM, Christoph Paasch wrote:
> Since commit eeea10b83a13 ("tcp: add
> tcp_v4_fill_cb()/tcp_v4_restore_cb()"), tcp_vX_fill_cb is only called
> after tcp_filter(). That means, TCP_SKB_CB(skb)->end_seq still points to
> the IP-part of the cb.
>
> We thus should not mock with it, as this can trigger bugs (thanks
> syzkaller):
> [ 12.349396]
> ==================================================================
> [ 12.350188] BUG: KASAN: slab-out-of-bounds in
> ip6_datagram_recv_specific_ctl+0x19b3/0x1a20
> [ 12.351035] Read of size 1 at addr ffff88006adbc208 by task
> test_ip6_datagr/1799
>
> Setting end_seq is actually no more necessary in tcp_filter as it gets
> initialized later on in tcp_vX_fill_cb.
>
> Cc: Eric Dumazet <eduma...@google.com>
> Fixes: eeea10b83a13 ("tcp: add tcp_v4_fill_cb()/tcp_v4_restore_cb()")
> Signed-off-by: Christoph Paasch <cpaa...@apple.com>
> ---
> net/ipv4/tcp_ipv4.c | 9 +--------
> 1 file changed, 1 insertion(+), 8 deletions(-)
Good catch, thanks !
Signed-off-by: Eric Dumazet <eduma...@google.com>
