libfuse: fix thread cancel race

Exiting a worker my race with cancelling that same worker.  This caused a
segmenation fault.

Reported and tested by Anatol Pomozov

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/fuse_loop_mt.c b/lib/fuse_loop_mt.c
index 7ae5890..82e3001 100644
--- a/lib/fuse_loop_mt.c
+++ b/lib/fuse_loop_mt.c
@@ -241,9 +241,11 @@ int fuse_session_loop_mt(struct fuse_session *se)
 		while (!fuse_session_exited(se))
 			sem_wait(&mt.finish);
 
+		pthread_mutex_lock(&mt.lock);
 		for (w = mt.main.next; w != &mt.main; w = w->next)
 			pthread_cancel(w->thread_id);
 		mt.exit = 1;
+		pthread_mutex_unlock(&mt.lock);
 
 		while (mt.main.next != &mt.main)
 			fuse_join_worker(&mt, mt.main.next);