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| author | Eryu Guan <guaneryu@gmail.com> | 2013-12-03 21:22:21 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-01-09 12:24:21 -0800 |
| commit | ae21dda05193c441bde106a4bbf88c185a68fbed (patch) | |
| tree | 314cbaa9b189dcae35444cb6d688c552f098f81a /fs/ext4 | |
| parent | e696abfcc89a087afef75ebca0848f37fb9877ae (diff) | |
ext4: check for overlapping extents in ext4_valid_extent_entries()
commit 5946d089379a35dda0e531710b48fca05446a196 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>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/extents.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index dc1e03047226..d480d49d2696 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -360,8 +360,10 @@ static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext) { ext4_fsblk_t block = ext4_ext_pblock(ext); int len = ext4_ext_get_actual_len(ext); + ext4_lblk_t lblock = le32_to_cpu(ext->ee_block); + ext4_lblk_t last = lblock + len - 1; - if (len == 0) + if (lblock > last) return 0; return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len); } @@ -387,11 +389,26 @@ static int ext4_valid_extent_entries(struct inode *inode, if (depth == 0) { /* leaf entries */ struct ext4_extent *ext = EXT_FIRST_EXTENT(eh); + struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; + ext4_fsblk_t pblock = 0; + ext4_lblk_t lblock = 0; + ext4_lblk_t prev = 0; + int len = 0; while (entries) { if (!ext4_valid_extent(inode, ext)) return 0; + + /* Check for overlapping extents */ + lblock = le32_to_cpu(ext->ee_block); + len = ext4_ext_get_actual_len(ext); + if ((lblock <= prev) && prev) { + pblock = ext4_ext_pblock(ext); + es->s_last_error_block = cpu_to_le64(pblock); + return 0; + } ext++; entries--; + prev = lblock + len - 1; } } else { struct ext4_extent_idx *ext_idx = EXT_FIRST_INDEX(eh); |