From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 688F71E0DD8; Wed, 30 Sep 2026 18:07:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791648; cv=none; b=HDSob6LhORXzODNSmNf/DH/H6F48voFBuGhXUObwuTcBYJDApvzKDWta3otlmuD1FbFkkmThsrMnZ6GPmLRmrN5qaK3v+iWDdf7wT6LBHqT9zr3WnUW7vjDGQlaJlU9VpFtEZPUmZnhft6OnsrxbX4BfGszVejwh5386xmHRTBY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791648; c=relaxed/simple; bh=HrGQVC1dT3MNXq28nM3ZvkscPWMIG0Kt5Hfx4Pj+dRg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nY2YpAi0E5rff3KbM0+9G0Op8OJw8+tSVL+/27IJMuJX7QSChLx9xQX/VAxFj/SWg5WrTjnQk+wRUmFi9WpWgYfMdm91qtTRWLVUJjIZlwujDOA2uH3Mof3hapjXNZ/KQjv7jOpalKgbEQQHVgtYsKMc42z2Vs4KzxSbRXsg6G4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cGIx3V5g; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cGIx3V5g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2EE81F00898; Wed, 30 Sep 2026 18:07:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791647; bh=ZUpTr4Zsizqg14h3uQFUfkyid4NcqPqS25N+2IHx2qo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=cGIx3V5gEAG1Q1uSCyScbYIgPZZeC1xBONJR/gDkEoVgZII1cVGqQm6TPLGj2dxR+ z9e/BSsymVbaWmf3sEQU8hfSRwoSlhMzMe1EY9bSbJI/E6DVFPMIpn/8ayxyVaFRgI uP5td/kr1zFDuNjbhvwJK5ifbfgBCySHbm3TJCow= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ali Ahmet Memis , Jan Kara , "Christian Brauner (Amutable)" Subject: [PATCH 5.15 377/752] ufs: validate cylinder group metadata before caching it Date: Wed, 30 Sep 2026 17:24:07 +0200 Message-ID: <20260930152406.437181470@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ali Ahmet Memis commit c9d263be26806d388129fab8c6904bed197fc6af upstream. ufs_read_cylinder() copies the cylinder group index and the rotor positions straight from the on-disk group and caches them without any check: ucpi->c_cgx = fs32_to_cpu(sb, ucg->cg_cgx); ucpi->c_rotor = fs32_to_cpu(sb, ucg->cg_rotor); ucpi->c_frotor = fs32_to_cpu(sb, ucg->cg_frotor); ucpi->c_irotor = fs32_to_cpu(sb, ucg->cg_irotor); They are then used as indices during allocation and free: - c_cgx indexes the cylinder summary array as UFS_SB(sb)->fs_cs(ucpi->c_cgx), so a value past s_ncg writes a 32 bit count outside the s_csp allocation. - c_frotor becomes a bitmap scan start, start = c_frotor >> 3, and then length = ((s_fpg + 7) >> 3) - start. A start beyond the block bitmap wraps the unsigned length to a huge value, so ubh_scanc() walks far past the cylinder group buffers. c_irotor drives the inode bitmap the same way. A crafted image can set any of these freely, turning an ordinary allocation into an out of bounds access. Reject a cylinder group whose recorded index does not match the group being read, or whose rotors fall outside the group, before the metadata is cached. Valid filesystems keep cg_cgx equal to the group number and the rotors within the group, so only malformed images are rejected. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Link: https://patch.msgid.link/20260801071306.59484-3-ali@iusegentoo.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman --- fs/ufs/cylinder.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/fs/ufs/cylinder.c +++ b/fs/ufs/cylinder.c @@ -66,6 +66,16 @@ static void ufs_read_cylinder (struct su ucpi->c_clustersumoff = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_clustersumoff); ucpi->c_clusteroff = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_clusteroff); ucpi->c_nclusterblks = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_nclusterblks); + + /* these on-disk values become array and bitmap indices */ + if (ucpi->c_cgx != cgno || + ucpi->c_rotor >= uspi->s_fpg || + ucpi->c_frotor >= uspi->s_fpg || + ucpi->c_irotor >= uspi->s_ipg) { + ufs_error(sb, __func__, + "inconsistent metadata in cylinder group %u\n", cgno); + goto failed; + } UFSD("EXIT\n"); return;