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 9F82F47DD5C; Mon, 31 Aug 2026 13:59:36 +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=1788184777; cv=none; b=VhWYY2/gxs59NNP9knxwD3yu5g8qVf14b6BZDzIDU1xkz3mJrQ8/FDRpydgCsu18F2WRBuoYQIlfqM80iqAB1Y3/qmDET9cHtcrxHayBhSpVhQLeVGqDKlU4RZ8CMJzp6aFCgDS0EP8hya7yy2OI8HoTfqRHnbuSdWvXpB1Yyl0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788184777; c=relaxed/simple; bh=9aZwEiIY2j4BidGb9E1Gxt5OI0abW/SUCRyr2z66Nrk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Wet+CY2xVXFd2Vjj/jFwpecWo0y0LDI5V876PBNQsgouA2Y1LxG3JDAGoaAGZr/2GWDmuFfM7MB1/RhgNotzCBEHk5G5c8B+/M6gUFmYWydOtOQzMhvDFQSEQyDRa3K6Aimt8AsLeT0gtjfAiyzD8np4AJRmrxVhUhwnGRrDLeM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yzH2U61j; 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="yzH2U61j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A92E1F000E9; Mon, 31 Aug 2026 13:59:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788184776; bh=NSZP+Da8Jkkk3ynv2t+nc/r0TkGl5aNWEQhq6VuWvoA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=yzH2U61j1kCfJDWCmb/mebYUDOtIQhFzL/NtU7vEW8ZE12mWIcGmsHty/+xXrrja3 +eUGHDbt6H7gnaeIp6o39T4sKtl3uItgLAa7Qq7feRBo1mYIpo2O2xkgZPio1RVEnU AnMKc512jCqvAuG5/jLtWZk7mJPJhO23e40oLToM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+b8d61a58b7c7ebd2c8e0@syzkaller.appspotmail.com, Christoph Hellwig , Jens Axboe , syzbot+2aca91e1d3ae43aef10c@syzkaller.appspotmail.com, =?UTF-8?q?Miguel=20Garc=C3=ADa?= , Sasha Levin Subject: [PATCH 6.1 35/92] block: make bio_check_eod work for zero sized devices Date: Mon, 31 Aug 2026 15:34:33 +0200 Message-ID: <20260831133401.526079712@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.482388899@linuxfoundation.org> References: <20260831133359.482388899@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Hellwig commit 3eb96946f0be6bf447cbdf219aba22bc42672f92 upstream. Since the dawn of time bio_check_eod has a check for a non-zero size of the device. This doesn't really make any sense as we never want to send I/O to a device that's been set to zero size, or never moved out of that. I am a bit surprised we haven't caught this for a long time, but the removal of the extra validation inside of zram caused syzbot to trip over this issue recently. I've added a Fixes tag for that commit, but the issue really goes back way before git history. Fixes: 9fe95babc742 ("zram: remove valid_io_request") Reported-by: syzbot+b8d61a58b7c7ebd2c8e0@syzkaller.appspotmail.com Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230524060538.1593686-1-hch@lst.de Signed-off-by: Jens Axboe Backport note for 6.1.y: The same underlying bug affects 6.1.y even though 9fe95babc742 is not in that tree. The syzbot reproducer attaches a socket to /dev/nbd0 without setting its capacity, then mounts it as BEFS. BEFS calls sb_bread() while bdev_nr_sectors() is zero. The maxsector guard makes bio_check_eod() accept that read, which reaches NBD and waits for a response instead of failing with -EIO. syzbot reproduced the resulting __bread_gfp() hang on 6.1.y and identified this upstream commit by fix bisection. Reported-by: syzbot+2aca91e1d3ae43aef10c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2aca91e1d3ae43aef10c Signed-off-by: Miguel García Signed-off-by: Sasha Levin --- block/blk-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-core.c b/block/blk-core.c index 25b4733f25d3d..1fcd80a1c54fd 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -515,7 +515,7 @@ static inline int bio_check_eod(struct bio *bio) sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); unsigned int nr_sectors = bio_sectors(bio); - if (nr_sectors && maxsector && + if (nr_sectors && (nr_sectors > maxsector || bio->bi_iter.bi_sector > maxsector - nr_sectors)) { pr_info_ratelimited("%s: attempt to access beyond end of device\n" -- 2.53.0