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 BFE9E33A6EB; Fri, 9 Oct 2026 14:35:22 +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=1791556524; cv=none; b=NJj4ja2QJMi10ABC8NNIpwbJj/FcwjE2X0b7qJ14xcKxs8IZEKYDYtcb5qs86FjRAuPK717TejIfJ1bYacJaEDk48dzx73fD85O9v35fRiY+ffrRt3qxGke2rKua+JdbUKFBYnLxqj+9G4w+j+I8/xUJmkLx/7ovTw7qjohqll4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791556524; c=relaxed/simple; bh=52eP73Ns4zHShTzwP2Suw0fGYEM2RSC1eK3dtsnNDZg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=DEdpg0vi0UP6gbnbnq0+NNe1K8xcpTix5H0Ql+nfYFVXWZV3BYH7p0PR0ED3W/E10tC+d3YDi4gWywxVbGxJU8Zg+svB/C1v3+Ft+zhFNiEu4YP0Mh3EHgDB004Ijk5Ie6p2dGMxqmzCUkUHupv6QAYy6vAHz1gBNigZBsEJJ/Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iSCqt44W; 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="iSCqt44W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD3F61F00899; Fri, 9 Oct 2026 14:35:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791556522; bh=hnoNwVrmVoDErOo06U3wCyMY7cKYgU0GBunzWgLF6yc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iSCqt44W8wXuoqKjC6gxcgD+wJ+JM/7vMxchFLbj8y/K6dkwWK3wMrfD0UMB6Xlzi h/j96sq9XqoZhTblEmUusk/qpWbs/Pkvu21mmSgPlcwN5EbCtZhK60vQ/+rzIrz6K2 dY2nG60rqEtpLqLM8Rnt+gq9lncTqyHLtHaRAJ6A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+b320a4d5f65a61dbbf89@syzkaller.appspotmail.com, =?UTF-8?q?J=C3=B6rn=20Engel?= , Pei Xiao , Miquel Raynal Subject: [PATCH 6.18 249/403] mtd: block2mtd: Fix divide error when erase_size is zero Date: Fri, 9 Oct 2026 16:10:10 +0200 Message-ID: <20261009140957.993010684@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261009140952.119038291@linuxfoundation.org> References: <20261009140952.119038291@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pei Xiao commit b5965c4221165045e19736794ca5f48ae3d67142 upstream. The erase size is parsed from the "block2mtd" module parameter and can be set to zero. add_device() then evaluates if (size % erase_size) with a zero divisor, which triggers a divide error: divide error: 0000 [#1] PREEMPT SMP PTI RIP: 0010:add_device drivers/mtd/devices/block2mtd.c:296 [inline] RIP: 0010:block2mtd_setup2+0x592/0xda0 drivers/mtd/devices/block2mtd.c:459 Call Trace: block2mtd_setup+0x27/0xe0 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x214/0x310 kernel/params.c:589 module_attr_store+0x65/0x90 kernel/params.c:904 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345 ... Reject a zero erase size before performing the modulo operation so the existing "erasesize must be a divisor of device size" error path reports the invalid argument and frees the device. Fixes: ea6d833a3fdd ("mtd: block2mtd: check device size") Reported-by: syzbot+b320a4d5f65a61dbbf89@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/6a7b58ba.ac361c09.22ff0a.0045.GAE@google.com/ Suggested-by: Jörn Engel Cc: stable@vger.kernel.org Signed-off-by: Pei Xiao Signed-off-by: Miquel Raynal Signed-off-by: Greg Kroah-Hartman --- drivers/mtd/devices/block2mtd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/mtd/devices/block2mtd.c +++ b/drivers/mtd/devices/block2mtd.c @@ -293,7 +293,7 @@ static struct block2mtd_dev *add_device( } size = bdev_nr_bytes(bdev); - if ((long)size % erase_size) { + if (!erase_size || (long)size % erase_size) { pr_err("erasesize must be a divisor of device size\n"); goto err_free_block2mtd; }