From d8f35e29d0e35a90f44c04de585470c211afddf9 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Fri, 7 Oct 2022 18:51:36 -0400 Subject: fix AS-safety of close when aio is in use and fd map is expanded the aio operations that lead to calling __aio_get_queue with the possibility to expand the fd map are not AS-safe, but if they are interrupted by a signal handler, the signal handler may call close, which is required to be AS-safe. due to __aio_get_queue taking the write lock without blocking signals, such a call to close from a signal handler could deadlock. change __aio_get_queue to block signals if it needs to obtain a write lock, and restore when finished. --- src/aio/aio.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'src') diff --git a/src/aio/aio.c b/src/aio/aio.c index 82f8eccb..d7e063bf 100644 --- a/src/aio/aio.c +++ b/src/aio/aio.c @@ -82,6 +82,8 @@ static size_t io_thread_stack_size; static struct aio_queue *__aio_get_queue(int fd, int need) { + sigset_t allmask, origmask; + int masked = 0; if (fd < 0) { errno = EBADF; return 0; @@ -93,6 +95,9 @@ static struct aio_queue *__aio_get_queue(int fd, int need) if ((!map || !map[a] || !map[a][b] || !map[a][b][c] || !(q=map[a][b][c][d])) && need) { pthread_rwlock_unlock(&maplock); if (fcntl(fd, F_GETFD) < 0) return 0; + sigfillset(&allmask); + masked = 1; + pthread_sigmask(SIG_BLOCK, &allmask, &origmask); pthread_rwlock_wrlock(&maplock); if (!io_thread_stack_size) { unsigned long val = __getauxval(AT_MINSIGSTKSZ); @@ -119,6 +124,7 @@ static struct aio_queue *__aio_get_queue(int fd, int need) if (q) pthread_mutex_lock(&q->lock); out: pthread_rwlock_unlock(&maplock); + if (masked) pthread_sigmask(SIG_SETMASK, &origmask, 0); return q; } -- cgit 1.4.1