From: Cong Wang <xiyou.wangc...@gmail.com> Date: Mon, 24 Jul 2017 10:07:32 -0700
> There are multiple reports showing we have a use-after-free in > the timer prb_retire_rx_blk_timer_expired(), where we use struct > tpacket_kbdq_core::pkbdq, a pg_vec, after it gets freed by > free_pg_vec(). > > The interesting part is it is not freed via packet_release() but > via packet_setsockopt(), which means we are not closing the socket. > Looking into the big and fat function packet_set_ring(), this could > happen if we satisfy the following conditions: > > 1. closing == 0, not on packet_release() path > 2. req->tp_block_nr == 0, we don't allocate a new pg_vec > 3. rx_ring->pg_vec is already set as V3, which means we already called > packet_set_ring() wtih req->tp_block_nr > 0 previously > 4. req->tp_frame_nr == 0, pass sanity check > 5. po->mapped == 0, never called mmap() > > In this scenario we are clearing the old rx_ring->pg_vec, so we need > to free this pg_vec, but we don't stop the timer on this path because > of closing==0. > > The timer has to be stopped as long as we need to free pg_vec, therefore > the check on closing!=0 is wrong, we should check pg_vec!=NULL instead. > > Thanks to liujian for testing different fixes. > > Reported-by: alexander.le...@verizon.com > Reported-by: Dave Jones <da...@codemonkey.org.uk> > Reported-by: liujian (CE) <liujia...@huawei.com> > Tested-by: liujian (CE) <liujia...@huawei.com> > Cc: Ding Tianhong <dingtianh...@huawei.com> > Cc: Willem de Bruijn <willemdebruijn.ker...@gmail.com> > Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com> Applied and queued up for -stable, thanks!
