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author | Eric Biggers <ebiggers@google.com> | 2018-04-12 11:48:09 -0400 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2018-04-12 11:48:09 -0400 |
commit | 349fa7d6e1935f49bf4161c4900711b2989180a9 (patch) | |
tree | c8df82a97c0681357988b5d7611679896727242a /fs/jbd2/transaction.c | |
parent | e40ff213898502d299351cc2fe1e350cd186f0d3 (diff) | |
download | linux-349fa7d6e1935f49bf4161c4900711b2989180a9.tar.bz2 |
ext4: prevent right-shifting extents beyond EXT_MAX_BLOCKS
During the "insert range" fallocate operation, extents starting at the
range offset are shifted "right" (to a higher file offset) by the range
length. But, as shown by syzbot, it's not validated that this doesn't
cause extents to be shifted beyond EXT_MAX_BLOCKS. In that case
->ee_block can wrap around, corrupting the extent tree.
Fix it by returning an error if the space between the end of the last
extent and EXT4_MAX_BLOCKS is smaller than the range being inserted.
This bug can be reproduced by running the following commands when the
current directory is on an ext4 filesystem with a 4k block size:
fallocate -l 8192 file
fallocate --keep-size -o 0xfffffffe000 -l 4096 -n file
fallocate --insert-range -l 8192 file
Then after unmounting the filesystem, e2fsck reports corruption.
Reported-by: syzbot+06c885be0edcdaeab40c@syzkaller.appspotmail.com
Fixes: 331573febb6a ("ext4: Add support FALLOC_FL_INSERT_RANGE for fallocate")
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/jbd2/transaction.c')
0 files changed, 0 insertions, 0 deletions