4.11-stable review patch. If anyone has any objections, please let me know.
------------------ From: Xin Long <[email protected]> [ Upstream commit 581409dacc9176b0de1f6c4ca8d66e13aa8e1b29 ] Now sctp holds read_lock when foreach sctp_ep_hashtable without disabling BH. If CPU schedules to another thread A at this moment, the thread A may be trying to hold the write_lock with disabling BH. As BH is disabled and CPU cannot schedule back to the thread holding the read_lock, while the thread A keeps waiting for the read_lock. A dead lock would be triggered by this. This patch is to fix this dead lock by calling read_lock_bh instead to disable BH when holding the read_lock in sctp_for_each_endpoint. Fixes: 626d16f50f39 ("sctp: export some apis or variables for sctp_diag and reuse some for proc") Reported-by: Xiumei Mu <[email protected]> Signed-off-by: Xin Long <[email protected]> Acked-by: Marcelo Ricardo Leitner <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/sctp/socket.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4586,13 +4586,13 @@ int sctp_for_each_endpoint(int (*cb)(str for (head = sctp_ep_hashtable; hash < sctp_ep_hashsize; hash++, head++) { - read_lock(&head->lock); + read_lock_bh(&head->lock); sctp_for_each_hentry(epb, &head->chain) { err = cb(sctp_ep(epb), p); if (err) break; } - read_unlock(&head->lock); + read_unlock_bh(&head->lock); } return err;
