[PATCH 5.15 004/128] ext4: check for out-of-order index extents in ext4_valid_extent_entries()

Greg Kroah-Hartman
2021-12-27T15:43:21Z

From: Zhang Yi <yi.zhang@huawei.com>

commit 8dd27fecede55e8a4e67eef2878040ecad0f0d33 upstream.

After commit 5946d089379a ("ext4: check for overlapping extents in
ext4_valid_extent_entries()"), we can check out the overlapping extent
entry in leaf extent blocks. But the out-of-order extent entry in index
extent blocks could also trigger bad things if the filesystem is
inconsistent. So this patch add a check to figure out the out-of-order
index extents and return error.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210908120850.4012324-2-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/extents.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -370,6 +370,9 @@ static int ext4_valid_extent_entries(str
ext4_fsblk_t *pblk, int depth)
{
unsigned short entries;
+ ext4_lblk_t lblock = 0;
+ ext4_lblk_t prev = 0;
+
if (eh->eh_entries == 0)
return 1;

@@ -378,31 +381,35 @@ static int ext4_valid_extent_entries(str
if (depth == 0) {
/* leaf entries */
struct ext4_extent *ext = EXT_FIRST_EXTENT(eh);
- 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) {
*pblk = ext4_ext_pblock(ext);
return 0;
}
+ prev = lblock + ext4_ext_get_actual_len(ext) - 1;
ext++;
entries--;
- prev = lblock + len - 1;
}
} else {
struct ext4_extent_idx *ext_idx = EXT_FIRST_INDEX(eh);
while (entries) {
if (!ext4_valid_extent_idx(inode, ext_idx))
return 0;
+
+ /* Check for overlapping index extents */
+ lblock = le32_to_cpu(ext_idx->ei_block);
+ if ((lblock <= prev) && prev) {
+ *pblk = ext4_idx_pblock(ext_idx);
+ return 0;
+ }
ext_idx++;
entries--;
+ prev = lblock;
}
}
return 1;