From nobody Sat Nov 15 05:39:06 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1755169061320304.64309924528845; Thu, 14 Aug 2025 03:57:41 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1umVdo-000713-KA; Thu, 14 Aug 2025 06:57:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1umVdk-00070j-PT for qemu-devel@nongnu.org; Thu, 14 Aug 2025 06:57:00 -0400 Received: from air.basealt.ru ([193.43.8.18]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1umVdh-0001cg-6t for qemu-devel@nongnu.org; Thu, 14 Aug 2025 06:57:00 -0400 Received: from boringlust.malta.altlinux.ru (obninsk.basealt.ru [217.15.195.17]) (Authenticated sender: rastyoginds) by air.basealt.ru (Postfix) with ESMTPSA id 14FE1233B2; Thu, 14 Aug 2025 13:56:53 +0300 (MSK) From: gerben@altlinux.org To: qemu-devel@nongnu.org, richard.henderson@linaro.org, peter.maydell@linaro.org Cc: sdl.qemu@linuxtesting.org Subject: [PATCH v2] linux-user: prevent NULL dereference in do_sendrecvmsg_locked() Date: Thu, 14 Aug 2025 13:56:01 +0300 Message-ID: <20250814105649.13521-1-gerben@altlinux.org> X-Mailer: git-send-email 2.42.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=193.43.8.18; envelope-from=gerben@altlinux.org; helo=air.basealt.ru X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1755169062330116600 Content-Type: text/plain; charset="utf-8" From: Denis Rastyogin fd_trans_target_to_host_data() in do_sendrecvmsg_locked() may be called when msg.msg_iov is NULL, for example when sending with MSG_MORE and no actual iovec data is present. Dereferencing msg.msg_iov in this case would lead to a NULL pointer access. Found by Linux Verification Center (linuxtesting.org) with SVACE. Reported-by: Alexey Appolonov Signed-off-by: Denis Rastyogin --- linux-user/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 59b2080b98..c7e6c53f08 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -3300,7 +3300,7 @@ static abi_long do_sendrecvmsg_locked(int fd, struct = target_msghdr *msgp, msg.msg_iov =3D vec; =20 if (send) { - if (fd_trans_target_to_host_data(fd)) { + if (fd_trans_target_to_host_data(fd) && msg.msg_iov) { void *host_msg; =20 host_msg =3D g_malloc(msg.msg_iov->iov_len); --=20 2.42.2