mptcp: fix infinite loop on recvmsg()/worker() race.
If recvmsg() and the workqueue race to dequeue the data pending on some subflow, the current mapping for such subflow covers several skbs and some of them have not reached yet the received, either the worker or recvmsg() can find a subflow with the data_avail flag set - since the current mapping is valid and in sequence - but no skbs in the receive queue - since the other entity just processed them. The above will lead to an unbounded loop in __mptcp_move_skbs() and a subsequent hang of any task trying to acquiring the msk socket lock. This change addresses the issue stopping the __mptcp_move_skbs() loop as soon as we detect the above race (empty receive queue with data_avail set). Reported-and-tested-by: <syzbot+fcf8ca5817d6e92c6567@syzkaller.appspotmail.com> Fixes: ab174ad8 ("mptcp: move ooo skbs into msk out of order queue.") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Please register or sign in to comment