From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailgw.kylinos.cn (mailgw.kylinos.cn [124.126.103.232]) (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 AFFB328315D; Thu, 13 Aug 2026 02:30:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=124.126.103.232 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786588229; cv=none; b=oQtfJ5y2IE2HDXCAhlySF7rBiOqdbAqEw+wcngP5DVeQ9XUM72t95zWFHeJ3fNdun23/M5SJevVx2L3hTowQnUWg6nRsp1ysoNUdlje9IIqsT59siJje2wU5KU2D2W1hYLR2TDzrLXr8D7CjDY3R/7djsE4coAKVJL8lV4ip+cU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786588229; c=relaxed/simple; bh=W7gk/5CUn5HfspyvfuqOqFjVbHTVdbkS7G22rQvyL8o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HuhkayLVEVepngHS6EuXX5H//YEWH4Kt8B4CeaqWT0G3eEnlhkNr3t9z1WGF8oolp+uMoFXxMyyWoSpbrrJxdAbP++fLEFbLIeJ2RiZtqD4OhEJCdW+W+ftWFf1tsOEgBLnvFQkBvkPzC9eR2ITQr1L7JELpcxXsPDowEAc4dtc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn; spf=pass smtp.mailfrom=kylinos.cn; arc=none smtp.client-ip=124.126.103.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kylinos.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kylinos.cn X-UUID: e94d988896be11f1aa26b74ffac11d73-20260813 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.12,REQID:bc36ddf7-17e3-4ca7-972f-1ec92ae09724,IP:0,U RL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:e7bac3a,CLOUDID:610e7a24874f7a441ed3247224c58302,BulkI D:nil,BulkQuantity:0,Recheck:0,SF:80|81|82|83|102|136|865|898,TC:nil,Conte nt:0|15|52,EDM:-3|-100,IP:nil,URL:99|1,File:nil,RT:nil,Bulk:nil,QS:nil,BEC :nil,COL:0,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE:0,ARC:0 X-CID-BVR: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR,TF_CID_SPAM_ULS X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: e94d988896be11f1aa26b74ffac11d73-20260813 X-User: xiaopei01@kylinos.cn Received: from [10.42.12.251] [(10.44.16.150)] by mailgw.kylinos.cn (envelope-from ) (Generic MTA with TLSv1.3 TLS_AES_128_GCM_SHA256 128/128) with ESMTP id 304537387; Thu, 13 Aug 2026 10:30:12 +0800 Message-ID: <00cf942e-4e0e-43b6-b4fb-3dc1e50a158a@kylinos.cn> Date: Thu, 13 Aug 2026 10:30:10 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mtd: block2mtd: Fix divide error when erase_size is zero To: Miquel Raynal Cc: joern@lazybastard.org, richard@nod.at, vigneshr@ti.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, syzbot+b320a4d5f65a61dbbf89@syzkaller.appspotmail.com, =?UTF-8?Q?J=C3=B6rn_Engel?= , stable@vger.kernel.org References: <48230456575d27aa83ce8640de8fc07cc62e8efb.1786499433.git.xiaopei01@kylinos.cn> <871pc3msar.fsf@bootlin.com> From: Pei Xiao In-Reply-To: <871pc3msar.fsf@bootlin.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 在 2026/8/12 20:34, Miquel Raynal 写道: > On 12/08/2026 at 09:52:42 +08, Pei Xiao wrote: > >> 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. >> >> While at it, drop the unnecessary (long) cast from the size operand of >> the modulo. >> >> 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 > > Apparently, removing the cast leads to an unsupported operation with a > 64-bit operand on 32-bit architectures (See Sashiko report). Using i386 for testing does reveal compilation issues; I will retain this (long) cast and send the third version of the patch. make ARCH=i386 -j$(nproc) ld: drivers/mtd/devices/block2mtd.o: in function `block2mtd_setup2': block2mtd.c:(.text+0x315): undefined reference to `__moddi3' make[2]: *** [scripts/Makefile.vmlinux:72：vmlinux.unstripped] 错误 1 > > I guess it is best to keep that cast in the end. > > Sorry for the changes back-and-forth. It is my pleasure. Pei. > > Miquèl