From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 537631BD515; Wed, 5 Jun 2024 11:56:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717588582; cv=none; b=D+O7XF9ELjTXrDffQKKGOc0GXJlohBQB/YYWo0T7IV3/mEIBTuJLM+SgH1aSeTK4fW8RwCNa9tOrhD2J8DR0qFXkf+qxtNtVSWBC4JNrShP68KNStKwvx4b2/X4i+AKsXBOqkCKutrgV8JbsbT4KqICP5Pb4R8h3AIt4oBYFwbY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717588582; c=relaxed/simple; bh=d40pCCEkuKjon/8B72AMqtYwBOiL7AlEvf0kD1jsMRg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Juxmu0wrqh9AaGL3V4mzaOKpfisb2iSY6c2UiRRDolik1qttrOLMdOwPOaEgb4BZXi561KlmjvcUvVYnN2TJh9W6ttQ1zTR10/88zHa3UJIlDwr+tP4a50E37uQbcYdhifdPeQyz51bPyZdFh23fP7rq58tYGCxcQAgqrjkFXKQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pnhknYVA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pnhknYVA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34697C4AF08; Wed, 5 Jun 2024 11:56:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717588582; bh=d40pCCEkuKjon/8B72AMqtYwBOiL7AlEvf0kD1jsMRg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pnhknYVAV4g5ALYh+pgDCCR+I+blNhcqfgBjxcMEgan4+gJ3AS5tiTkFxdQKJshtK 4wTFuKIqfeazNLvrSc0U5wzOd3cxZ+6K4bvTEHCbdySQDSKB6z9T/DVIrAZKOKkncb zVabeFswb5HSahpY+NeC2CQRVVVzUZvI4TWRDREItb72nic4G4eEifKVLYgVIDtk8r svznGIqwL+JKXroazaiC2tu012qJIJvMbkb9+SDiB+TtA8hhcp+01kS3pfcZkjEfdt 1v+dQCJoLEp/VEs29ngvSKmHhzWQPKKGOHxIwfzRJrxI4suOYrQ4K7+FCEU3DeD76R YTGUrgl7w/NvQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Justin Stitt , linux-hardening@vger.kernel.org, Phillip Potter , Jens Axboe , Sasha Levin , nathan@kernel.org, llvm@lists.linux.dev Subject: [PATCH AUTOSEL 6.6 2/4] cdrom: rearrange last_media_change check to avoid unintentional overflow Date: Wed, 5 Jun 2024 07:56:14 -0400 Message-ID: <20240605115619.2965224-2-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240605115619.2965224-1-sashal@kernel.org> References: <20240605115619.2965224-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.32 Content-Transfer-Encoding: 8bit From: Justin Stitt [ Upstream commit efb905aeb44b0e99c0e6b07865b1885ae0471ebf ] When running syzkaller with the newly reintroduced signed integer wrap sanitizer we encounter this splat: [ 366.015950] UBSAN: signed-integer-overflow in ../drivers/cdrom/cdrom.c:2361:33 [ 366.021089] -9223372036854775808 - 346321 cannot be represented in type '__s64' (aka 'long long') [ 366.025894] program syz-executor.4 is using a deprecated SCSI ioctl, please convert it to SG_IO [ 366.027502] CPU: 5 PID: 28472 Comm: syz-executor.7 Not tainted 6.8.0-rc2-00035-gb3ef86b5a957 #1 [ 366.027512] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 366.027518] Call Trace: [ 366.027523] [ 366.027533] dump_stack_lvl+0x93/0xd0 [ 366.027899] handle_overflow+0x171/0x1b0 [ 366.038787] ata1.00: invalid multi_count 32 ignored [ 366.043924] cdrom_ioctl+0x2c3f/0x2d10 [ 366.063932] ? __pm_runtime_resume+0xe6/0x130 [ 366.071923] sr_block_ioctl+0x15d/0x1d0 [ 366.074624] ? __pfx_sr_block_ioctl+0x10/0x10 [ 366.077642] blkdev_ioctl+0x419/0x500 [ 366.080231] ? __pfx_blkdev_ioctl+0x10/0x10 ... Historically, the signed integer overflow sanitizer did not work in the kernel due to its interaction with `-fwrapv` but this has since been changed [1] in the newest version of Clang. It was re-enabled in the kernel with Commit 557f8c582a9ba8ab ("ubsan: Reintroduce signed overflow sanitizer"). Let's rearrange the check to not perform any arithmetic, thus not tripping the sanitizer. Link: https://github.com/llvm/llvm-project/pull/82432 [1] Closes: https://github.com/KSPP/linux/issues/354 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Link: https://lore.kernel.org/lkml/20240507-b4-sio-ata1-v1-1-810ffac6080a@google.com Reviewed-by: Phillip Potter Link: https://lore.kernel.org/lkml/ZjqU0fbzHrlnad8D@equinox Signed-off-by: Phillip Potter Link: https://lore.kernel.org/r/20240507222520.1445-2-phil@philpotter.co.uk Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/cdrom/cdrom.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index cc28398059833..01f46caf1f88b 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -2358,7 +2358,7 @@ static int cdrom_ioctl_timed_media_change(struct cdrom_device_info *cdi, return -EFAULT; tmp_info.media_flags = 0; - if (tmp_info.last_media_change - cdi->last_media_change_ms < 0) + if (cdi->last_media_change_ms > tmp_info.last_media_change) tmp_info.media_flags |= MEDIA_CHANGED_FLAG; tmp_info.last_media_change = cdi->last_media_change_ms; -- 2.43.0