ext4: check for zero length extent

commit 31d4f3a upstream. Explicitly test for an extent whose length is zero, and flag that as a corrupted extent. This avoids a kernel BUG_ON assertion failure. Tested: Without this patch, the file system image found in tests/f_ext_zero_len/image.gz in the latest e2fsprogs sources causes a kernel panic. With this patch, an ext4 file system error is noted instead, and the file system is marked as being corrupted. https://bugzilla.kernel.org/show_bug.cgi?id=42859 Signed-off-by: "Theodore Ts'o" <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
faux123 · Apr 2, 2012 · 471320c · 471320c
1 parent df3c660
commit 471320c
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
@@ -341,6 +341,8 @@ 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);
 
+	if (len == 0)
+		return 0;
 	return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
 }