From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44425 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932176AbcHNShh (ORCPT ); Sun, 14 Aug 2016 14:37:37 -0400 Subject: Patch "ext4: validate s_reserved_gdt_blocks on mount" has been added to the 4.4-stable tree To: tytso@mit.edu, gregkh@linuxfoundation.org, vegard.nossum@oracle.com Cc: , From: Date: Sun, 14 Aug 2016 20:37:22 +0200 Message-ID: <147119984214012@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled ext4: validate s_reserved_gdt_blocks on mount to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-validate-s_reserved_gdt_blocks-on-mount.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 5b9554dc5bf008ae7f68a52e3d7e76c0920938a2 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 5 Jul 2016 20:01:52 -0400 Subject: ext4: validate s_reserved_gdt_blocks on mount From: Theodore Ts'o commit 5b9554dc5bf008ae7f68a52e3d7e76c0920938a2 upstream. If s_reserved_gdt_blocks is extremely large, it's possible for ext4_init_block_bitmap(), which is called when ext4 sets up an uninitialized block bitmap, to corrupt random kernel memory. Add the same checks which e2fsck has --- it must never be larger than blocksize / sizeof(__u32) --- and then add a backup check in ext4_init_block_bitmap() in case the superblock gets modified after the file system is mounted. Reported-by: Vegard Nossum Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/balloc.c | 3 +++ fs/ext4/super.c | 7 +++++++ 2 files changed, 10 insertions(+) --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -208,6 +208,9 @@ static int ext4_init_block_bitmap(struct memset(bh->b_data, 0, sb->s_blocksize); bit_max = ext4_num_base_meta_clusters(sb, block_group); + if ((bit_max >> 3) >= bh->b_size) + return -EFSCORRUPTED; + for (bit = 0; bit < bit_max; bit++) ext4_set_bit(bit, bh->b_data); --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3372,6 +3372,13 @@ static int ext4_fill_super(struct super_ goto failed_mount; } + if (le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) > (blocksize / 4)) { + ext4_msg(sb, KERN_ERR, + "Number of reserved GDT blocks insanely large: %d", + le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks)); + goto failed_mount; + } + if (sbi->s_mount_opt & EXT4_MOUNT_DAX) { if (blocksize != PAGE_SIZE) { ext4_msg(sb, KERN_ERR, Patches currently in stable-queue which might be from tytso@mit.edu are queue-4.4/ext4-fix-deadlock-during-page-writeback.patch queue-4.4/ext4-short-cut-orphan-cleanup-on-error.patch queue-4.4/ext4-check-for-extents-that-wrap-around.patch queue-4.4/ext4-validate-s_reserved_gdt_blocks-on-mount.patch queue-4.4/ext4-don-t-call-ext4_should_journal_data-on-the-journal-inode.patch queue-4.4/random-strengthen-input-validation-for-rndaddtoentcnt.patch