ext4: avoid divide by zero fault when deleting corrupted inline directories
commit 4d982e25d0bdc83d8c64e66fdeca0b89240b3b85 upstream.
A specially crafted file system can trick empty_inline_dir() into
reading past the last valid entry in a inline directory, and then run
into the end of xattr marker. This will trigger a divide by zero
fault. Fix this by using the size of the inline directory instead of
dir->i_size.
Also clean up error reporting in __ext4_check_dir_entry so that the
message is clearer and more understandable --- and avoids the division
by zero trap if the size passed in is zero. (I'm not sure why we
coded it that way in the first place; printing offset % size is
actually more confusing and less useful.)
https://bugzilla.kernel.org/show_bug.cgi?id=200933
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Wen Xu <wen.xu@gatech.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index e8b3650..e16bc4c 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -74,7 +74,7 @@
else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))
error_msg = "rec_len is too small for name_len";
else if (unlikely(((char *) de - buf) + rlen > size))
- error_msg = "directory entry across range";
+ error_msg = "directory entry overrun";
else if (unlikely(le32_to_cpu(de->inode) >
le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))
error_msg = "inode out of bounds";
@@ -83,18 +83,16 @@
if (filp)
ext4_error_file(filp, function, line, bh->b_blocknr,
- "bad entry in directory: %s - offset=%u(%u), "
- "inode=%u, rec_len=%d, name_len=%d",
- error_msg, (unsigned) (offset % size),
- offset, le32_to_cpu(de->inode),
- rlen, de->name_len);
+ "bad entry in directory: %s - offset=%u, "
+ "inode=%u, rec_len=%d, name_len=%d, size=%d",
+ error_msg, offset, le32_to_cpu(de->inode),
+ rlen, de->name_len, size);
else
ext4_error_inode(dir, function, line, bh->b_blocknr,
- "bad entry in directory: %s - offset=%u(%u), "
- "inode=%u, rec_len=%d, name_len=%d",
- error_msg, (unsigned) (offset % size),
- offset, le32_to_cpu(de->inode),
- rlen, de->name_len);
+ "bad entry in directory: %s - offset=%u, "
+ "inode=%u, rec_len=%d, name_len=%d, size=%d",
+ error_msg, offset, le32_to_cpu(de->inode),
+ rlen, de->name_len, size);
return 1;
}