From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793211413; b=z5zuht++/WS1yDRWJlbnk/6bBh5Th2R+2jpqJMJQ0GLFnue8eCC8hR9gdOnuw+wPZSlx ITboFAHnN4uqZK3DorZjFrs4IZXCRzeRvJb447QtSHnwlttITzotvqQ5r5B03q4Q6y8T6 gJHRXlvhCDfMAWoSb/ynMfaqjrXK8iOMwJGHgE4EDDH5lQPEhQvzj/JOmL2iNHKx8gmst uUovgQIrU6XA69UyVF8Oz/olAlO/bpwtMPj4BUNiMwW4vrnckO9HHNH3qofGSa010HStn hDH2xMx4npIzVbVEpbPtP+j4pVDQmcT3TP0vHa4NhHIu/3tmMHTPtfj52ah/1bjs1kg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211413; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=ualmab7h67fCS954UpAY6pNKBpqsrPiXaTC/Kc/jLIk=; b=ZlvbqTJ7r9mUgPm25bk6Q7ioSomEvTnfFeLxzZXlRX/MxDI+pGf/pE9AU680DOwF6q5D iTbbfHuGcaje2RU/eiVe5LSLhteay5KP0KMBXqqrKO5Tf8RMrDBlZZGXFCtPlhzwiaxfO m+Y6ClEuzB3F53b3oHv0ucM76r747tjkQHtC/XsITRFsrYg6Mxqnz7dKPMYOnmVAGVc5q fwixfnM9443v/JTGV80pR6B8m+MRNOWa/nNsUNplAFp+VIA7ZxrU1a2jvSpsY78hJ2sYF eW0jFWFigy0F9khUkUah3UxV3KyjniJlDHkey1ChRAg1iisE5C79HOAsWshxdKPhckA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=AP0m0NRr; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 585E7606A326; Wed, 28 Oct 2026 18:16:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=AP0m0NRr Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8D0C1F01825; Wed, 28 Oct 2026 18:16:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211413; bh=ualmab7h67fCS954UpAY6pNKBpqsrPiXaTC/Kc/jLIk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AP0m0NRr0jLxfZxfTt9ZFhEBp4tfkXGwmb5sSOephu8h6eJOsQRMM2fYBQ1af4D4s pwllv4d7pYFjJLIf0N9rCyjDXD60kQaCusxyoHWsUZkfZFHWXh0DmdU+rzO+ZkKHX6 HrJ0Oa2F8lMk7aenOObzhFNKPxi1BJNdtxVU9S7o= 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 , Sasha Levin Subject: [PATCH 5.15 323/571] mtd: block2mtd: Fix divide error when erase_size is zero Date: Wed, 28 Oct 2026 17:57:50 +0100 Message-ID: <20261028170015.669145456@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pei Xiao [ Upstream commit b5965c4221165045e19736794ca5f48ae3d67142 ] 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 [ sashal: adapted the size variable check to direct dev->blkdev->bd_inode->i_size access ] Signed-off-by: Sasha Levin --- drivers/mtd/devices/block2mtd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c index c08721b11642b..58ec5d0525ec2 100644 --- a/drivers/mtd/devices/block2mtd.c +++ b/drivers/mtd/devices/block2mtd.c @@ -269,7 +269,7 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size, goto err_free_block2mtd; } - if ((long)dev->blkdev->bd_inode->i_size % erase_size) { + if (!erase_size || (long)dev->blkdev->bd_inode->i_size % erase_size) { pr_err("erasesize must be a divisor of device size\n"); goto err_free_block2mtd; } -- 2.53.0