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 6EB4B298C1A; Mon, 12 May 2025 18:04:26 +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=1747073066; cv=none; b=C3i76RMHkcbi2m+fQDkglVP4mjikKDwGJagooIiXZ1QdXKl7WQFgl+mXZHrE2a1MVc3zQi65vI82NOZIVPFcfXMPHegeekYRrftLKSz3810UPJxCwlNqIwwNAlzYRZZxAEPKDR/o5Cw0zhkErdsuSBZFZKb/r1KGlwcqan0x1So= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747073066; c=relaxed/simple; bh=xe/yd5hY9F/c7KpezlLnUK454tNnJ0eM9dMDV1J9e/4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NohzNA55gspVOvBdfcG50/OrBNkpNVY0w8MKZcswc4TmdQjVzDEEdGqEzsNaD6W2SaTAJv3TJOYK0/jjBgJeeQ/+NN13GCnSEdo0jL/c04+LUD6ZOV0OnF0dbPjo47+deWJTLBTNXbiWsTGr62wbBnbfScJGf+HQwkBaR0NtLz8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=e93sx00j; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="e93sx00j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1D7AC4CEE7; Mon, 12 May 2025 18:04:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1747073066; bh=xe/yd5hY9F/c7KpezlLnUK454tNnJ0eM9dMDV1J9e/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e93sx00jHOCFHGUIcDlVo9iUZMCFK5H8FXQmb0/+lL1A+D7UJEnq/dzIzFkJagBKJ C43diqkd3ustih7jvEH6sqOh3/Zl2l42cFh7JPtWymhcww/2rq7ie2Pl4KMnqPcuLG 0rfOlwA9VUOOw7mftfD9NuQV5+X0pXqUb2MaJh0c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+6af973a3b8dfd2faefdc@syzkaller.appspotmail.com, Lizhi Xu , Christoph Hellwig , Jens Axboe , Sasha Levin Subject: [PATCH 6.12 144/184] loop: Add sanity check for read/write_iter Date: Mon, 12 May 2025 19:45:45 +0200 Message-ID: <20250512172047.669780379@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250512172041.624042835@linuxfoundation.org> References: <20250512172041.624042835@linuxfoundation.org> User-Agent: quilt/0.68 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-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lizhi Xu [ Upstream commit f5c84eff634ba003326aa034c414e2a9dcb7c6a7 ] Some file systems do not support read_iter/write_iter, such as selinuxfs in this issue. So before calling them, first confirm that the interface is supported and then call it. It is releavant in that vfs_iter_read/write have the check, and removal of their used caused szybot to be able to hit this issue. Fixes: f2fed441c69b ("loop: stop using vfs_iter__{read,write} for buffered I/O") Reported-by: syzbot+6af973a3b8dfd2faefdc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=6af973a3b8dfd2faefdc Signed-off-by: Lizhi Xu Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20250428143626.3318717-1-lizhi.xu@windriver.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/loop.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e083099a01e29..6bd44ec2c9b1a 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -501,6 +501,17 @@ static void loop_assign_backing_file(struct loop_device *lo, struct file *file) lo->old_gfp_mask & ~(__GFP_IO | __GFP_FS)); } +static int loop_check_backing_file(struct file *file) +{ + if (!file->f_op->read_iter) + return -EINVAL; + + if ((file->f_mode & FMODE_WRITE) && !file->f_op->write_iter) + return -EINVAL; + + return 0; +} + /* * loop_change_fd switched the backing store of a loopback device to * a new file. This is useful for operating system installers to free up @@ -521,6 +532,10 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, if (!file) return -EBADF; + error = loop_check_backing_file(file); + if (error) + return error; + /* suppress uevents while reconfiguring the device */ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1); @@ -953,6 +968,14 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode, if (!file) return -EBADF; + + if ((mode & BLK_OPEN_WRITE) && !file->f_op->write_iter) + return -EINVAL; + + error = loop_check_backing_file(file); + if (error) + return error; + is_loop = is_loop_device(file); /* This is safe, since we have a reference from open(). */ -- 2.39.5