From nobody Thu Apr 3 10:15:33 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 1742293239183884.4236972435708; Tue, 18 Mar 2025 03:20:39 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tuU3V-0006HZ-4x; Tue, 18 Mar 2025 06:20:21 -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 1tuU2y-00064S-02 for qemu-devel@nongnu.org; Tue, 18 Mar 2025 06:19:44 -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 1tuU2v-000862-TE for qemu-devel@nongnu.org; Tue, 18 Mar 2025 06:19:43 -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 D77B420004; Tue, 18 Mar 2025 13:19:36 +0300 (MSK) From: gerben@altlinux.org To: qemu-devel@nongnu.org, kwolf@redhat.com, hreitz@redhat.com Cc: sdl.qemu@linuxtesting.org, Denis Rastyogin Subject: [PATCH] qemu-img: fix division by zero in bench_cb() for zero-sized images Date: Tue, 18 Mar 2025 13:19:00 +0300 Message-ID: <20250318101933.255617-1-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: 1742293242368019000 Content-Type: text/plain; charset="utf-8" From: Denis Rastyogin This error was discovered by fuzzing qemu-img. This commit fixes a division by zero error in the bench_cb() function that occurs when using the bench command with a zero-sized image. The issue arises because b->image_size can be zero, leading to a division by zero in the modulo operation (b->offset %=3D b->image_size). This patch adds a check for b->image_size =3D=3D 0 and resets b->offset to 0 in such cases, preventing the error. Signed-off-by: Denis Rastyogin --- qemu-img.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/qemu-img.c b/qemu-img.c index 89c93c1eb5..2044c22a4c 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -4488,7 +4488,11 @@ static void bench_cb(void *opaque, int ret) */ b->in_flight++; b->offset +=3D b->step; - b->offset %=3D b->image_size; + if (b->image_size =3D=3D 0) { + b->offset =3D 0; + } else { + b->offset %=3D b->image_size; + } if (b->write) { acb =3D blk_aio_pwritev(b->blk, offset, b->qiov, 0, bench_cb, = b); } else { --=20 2.42.2