From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF1FFC77B7D for ; Wed, 10 May 2023 14:40:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237484AbjEJOkX (ORCPT ); Wed, 10 May 2023 10:40:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237479AbjEJOkT (ORCPT ); Wed, 10 May 2023 10:40:19 -0400 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F97A86B9; Wed, 10 May 2023 07:40:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1683729613; bh=koxG1YCExChvSpEVnSP+x7jAE+o8CIdHy2OpuhUjaJg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=X+qHB8fvNCw86u2Cujt2PHfki8wfPRHo4zgUTEq//5z1JDq17dYGK3uB7vP5e0S0R Bge8beofZdAA74v47nAg84hxdELO/93OMfR3OG5PNoqppBsiIcijmNimfN3jysxa87 lu5FLpbOjJhh3kXyehlDc1p8aEZHux8VbSj4ijeu7UFCqIJOHnw5NdE0C/20R+puGn 6Jr8KlS/oesyVLJlzV4fcHynNp1il8G3FbBwHNj9Duq1ErXXYIAOLLBtdCPPmvvhP8 zHsG0wDAKtJfXuc9IB2hx+czdDR+gOk5Zk/jT2aaSLVXjRR2Is2ZcANP0e6FcT/4dI fkScEkT1F/XHQ== Received: from integral2.. (unknown [101.128.114.135]) by gnuweeb.org (Postfix) with ESMTPSA id C6E48245CF5; Wed, 10 May 2023 21:40:10 +0700 (WIB) From: Ammar Faizi To: Jens Axboe Cc: Ammar Faizi , =?UTF-8?q?Barnab=C3=A1s=20P=C5=91cze?= , Michael William Jonathan , Linux Kernel Mailing List , io-uring Mailing List , GNU/Weeb Mailing List Subject: [PATCH liburing v1 1/2] recv-msgall: Fix undefined behavior in `recv_prep()` Date: Wed, 10 May 2023 21:39:26 +0700 Message-Id: <20230510143927.123170-2-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230510143927.123170-1-ammarfaizi2@gnuweeb.org> References: <20230510143927.123170-1-ammarfaizi2@gnuweeb.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 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 --- 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