linux.git/fs/ext4/balloc.c, branch v5.2

ext4: use ext4_warning() for sb_getblk failure

2018-08-01T16:02:31+00:00

Out of memory should not be considered as critical errors; so replace
ext4_error() with ext4_warnig().

Signed-off-by: Wang Shilong 
Signed-off-by: Theodore Ts'o 
Cc: stable@vger.kernel.org

ext4: check for allocation block validity with block group locked

2018-07-12T23:08:05+00:00

With commit 044e6e3d74a3: "ext4: don't update checksum of new
initialized bitmaps" the buffer valid bit will get set without
actually setting up the checksum for the allocation bitmap, since the
checksum will get calculated once we actually allocate an inode or
block.

If we are doing this, then we need to (re-)check the verified bit
after we take the block group lock.  Otherwise, we could race with
another process reading and verifying the bitmap, which would then
complain about the checksum being invalid.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1780137

Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org

ext4: only look at the bg_flags field if it is valid

2018-06-14T04:58:00+00:00

The bg_flags field in the block group descripts is only valid if the
uninit_bg or metadata_csum feature is enabled.  We were not
consistently looking at this field; fix this.

Also block group #0 must never have uninitialized allocation bitmaps,
or need to be zeroed, since that's where the root inode, and other
special inodes are set up.  Check for these conditions and mark the
file system as corrupted if they are detected.

This addresses CVE-2018-10876.

https://bugzilla.kernel.org/show_bug.cgi?id=199403

Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org

ext4: always check block group bounds in ext4_init_block_bitmap()

2018-06-14T03:00:48+00:00

Regardless of whether the flex_bg feature is set, we should always
check to make sure the bits we are setting in the block bitmap are
within the block group bounds.

https://bugzilla.kernel.org/show_bug.cgi?id=199865

Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org

ext4: mark block bitmap corrupted when found

2018-05-12T16:37:58+00:00

There are still some cases that we missed to set
block bitmaps corrupted bit properly:

1) block bitmap number is wrong.
2) failed to read block bitmap due to disk errors.
3) double free block bitmaps..
4) some mismatch check with bitmaps vs buddy information.

Signed-off-by: Theodore Ts'o 
Signed-off-by: Liu Bo 
Signed-off-by: Wang Shilong 
Reviewed-by: Liu Bo 
Reviewed-by: Andreas Dilger

ext4: add new ext4_mark_group_bitmap_corrupted() helper

2018-05-12T15:39:40+00:00

Since there are many places to set inode/block bitmap
corrupt bit, add a new helper for it, which will make
codes more clear.

Signed-off-by: Wang Shilong 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Andreas Dilger

ext4: fix bitmap position validation

2018-04-24T15:31:44+00:00

Currently in ext4_valid_block_bitmap() we expect the bitmap to be
positioned anywhere between 0 and s_blocksize clusters, but that's
wrong because the bitmap can be placed anywhere in the block group. This
causes false positives when validating bitmaps on perfectly valid file
system layouts. Fix it by checking whether the bitmap is within the group
boundary.

The problem can be reproduced using the following

mkfs -t ext3 -E stride=256 /dev/vdb1
mount /dev/vdb1 /mnt/test
cd /mnt/test
wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.3.tar.xz
tar xf linux-4.16.3.tar.xz

This will result in the warnings in the logs

EXT4-fs error (device vdb1): ext4_validate_block_bitmap:399: comm tar: bg 84: block 2774529: invalid block bitmap

[ Changed slightly for clarity and to not drop a overflow test -- TYT ]

Signed-off-by: Lukas Czerner 
Signed-off-by: Theodore Ts'o 
Reported-by: Ilya Dryomov 
Fixes: 7dac4a1726a9 ("ext4: add validity checks for bitmap block numbers")
Cc: stable@vger.kernel.org

ext4: add validity checks for bitmap block numbers

2018-03-27T03:54:10+00:00

An privileged attacker can cause a crash by mounting a crafted ext4
image which triggers a out-of-bounds read in the function
ext4_valid_block_bitmap() in fs/ext4/balloc.c.

This issue has been assigned CVE-2018-1093.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199181
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1560782
Reported-by: Wen Xu 
Signed-off-by: Theodore Ts'o 
Cc: stable@vger.kernel.org

ext4: don't update checksum of new initialized bitmaps

2018-02-19T19:16:47+00:00

When reading the inode or block allocation bitmap, if the bitmap needs
to be initialized, do not update the checksum in the block group
descriptor.  That's because we're not set up to journal those changes.
Instead, just set the verified bit on the bitmap block, so that it's
not necessary to validate the checksum.

When a block or inode allocation actually happens, at that point the
checksum will be calculated, and update of the bg descriptor block
will be properly journalled.

Signed-off-by: Theodore Ts'o 
Cc: stable@vger.kernel.org

ext4: use 'sbi' instead of 'EXT4_SB(sb)'

2018-01-11T18:17:49+00:00

We could use 'sbi' instead of 'EXT4_SB(sb)' to make code more elegant.

Signed-off-by: Jun Piao 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jan Kara