ext4: check for overlapping extents in ext4_valid_extent_entries()
A corrupted ext4 may have out of order leaf extents, i.e.
extent: lblk 0--1023, len 1024, pblk 9217, flags: LEAF UNINIT
extent: lblk 1000--2047, len 1024, pblk 10241, flags: LEAF UNINIT
^^^^ overlap with previous extent
Reading such extent could hit BUG_ON() in ext4_es_cache_extent().
BUG_ON(end < lblk);
The problem is that __read_extent_tree_block() tries to cache holes as
well but assumes 'lblk' is greater than 'prev' and passes underflowed
length to ext4_es_cache_extent(). Fix it by checking for overlapping
extents in ext4_valid_extent_entries().
I hit this when fuzz testing ext4, and am able to reproduce it by
modifying the on-disk extent by hand.
Also add the check for (ee_block + len - 1) in ext4_valid_extent() to
make sure the value is not overflow.
Ran xfstests on patched ext4 and no regression.
Cc: Lukáš Czerner <lczerner@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
1 file changed