ext4: check for zero length extent
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" <tytso@mit.edu>
Cc: stable@kernel.org
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 74f23c2..4394a757 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -300,6 +300,8 @@
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);
}