The lifetime of `struct msghdr msg;` must be long enough until the CQE is generated because the recvmsg operation will write to that storage. I found this test segfault when compiling with -O0 optimization. This is undefined behavior and may behave randomly. Fix this by making the lifetime of `struct msghdr msg;` long enough. Fixes: https://github.com/axboe/liburing/issues/855 Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx> --- test/recv-msgall.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) diff --git a/test/recv-msgall.c b/test/recv-msgall.c index ae123e4c381b2b1a..f809834b2e427fc5 100644 --- a/test/recv-msgall.c +++ b/test/recv-msgall.c @@ -18,14 +18,18 @@ #define MAX_MSG 128 #define HOST "127.0.0.1" static __be16 bind_port; +struct recv_data { + pthread_mutex_t mutex; + int use_recvmsg; + struct msghdr msg; +}; static int recv_prep(struct io_uring *ring, struct iovec *iov, int *sock, - int use_recvmsg) + struct recv_data *rd) { struct sockaddr_in saddr; struct io_uring_sqe *sqe; int sockfd, ret, val; - struct msghdr msg = { }; memset(&saddr, 0, sizeof(saddr)); saddr.sin_family = AF_INET; @@ -47,14 +51,17 @@ static int recv_prep(struct io_uring *ring, struct iovec *iov, int *sock, bind_port = saddr.sin_port; sqe = io_uring_get_sqe(ring); - if (!use_recvmsg) { + if (!rd->use_recvmsg) { io_uring_prep_recv(sqe, sockfd, iov->iov_base, iov->iov_len, MSG_WAITALL); } else { - msg.msg_namelen = sizeof(struct sockaddr_in); - msg.msg_iov = iov; - msg.msg_iovlen = 1; - io_uring_prep_recvmsg(sqe, sockfd, &msg, MSG_WAITALL); + struct msghdr *msg = &rd->msg; + + memset(msg, 0, sizeof(*msg)); + msg->msg_namelen = sizeof(struct sockaddr_in); + msg->msg_iov = iov; + msg->msg_iovlen = 1; + io_uring_prep_recvmsg(sqe, sockfd, msg, MSG_WAITALL); } sqe->user_data = 2; @@ -101,11 +108,6 @@ err: return 1; } -struct recv_data { - pthread_mutex_t mutex; - int use_recvmsg; -}; - static void *recv_fn(void *data) { struct recv_data *rd = data; @@ -128,7 +130,7 @@ static void *recv_fn(void *data) goto err; } - ret = recv_prep(&ring, &iov, &sock, rd->use_recvmsg); + ret = recv_prep(&ring, &iov, &sock, rd); if (ret) { fprintf(stderr, "recv_prep failed: %d\n", ret); goto err; -- Ammar Faizi
