[PATCH 4.19 36/58] ext4: check for out-of-order index extents in ext4_valid_extent_entries()

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

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@xxxxxxxxxx>
Reviewed-by: Theodore Ts'o <tytso@xxxxxxx>
Link: https://lore.kernel.org/r/20210908120850.4012324-2-yi.zhang@xxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Leah Rumancik <leah.rumancik@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ext4/extents.c |   21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -390,9 +390,12 @@ static int ext4_valid_extent_idx(struct
 
 static int ext4_valid_extent_entries(struct inode *inode,
 				struct ext4_extent_header *eh,
-				int depth)
+				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;
 
@@ -403,32 +406,36 @@ static int ext4_valid_extent_entries(str
 		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;
 			}
+			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;
@@ -462,7 +469,7 @@ static int __ext4_ext_check(const char *
 		error_msg = "invalid eh_entries";
 		goto corrupted;
 	}
-	if (!ext4_valid_extent_entries(inode, eh, depth)) {
+	if (!ext4_valid_extent_entries(inode, eh, &pblk, depth)) {
 		error_msg = "invalid extent entries";
 		goto corrupted;
 	}