ext4: check for overlapping extents in ext4_valid_extent_entries()
commit 5946d089 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Showing
Please register or sign in to comment