tree 70b2137f996f063a010b41aaa2932a281819461b
parent 1b891ce7e148c9bf1ad5e98c9997e24a804cf2e2
author Jan Kara <jack@suse.cz> 1575306132 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1578141622 +0100

ext4: fix ext4_empty_dir() for directories with holes

commit 64d4ce892383b2ad6d782e080d25502f91bf2a38 upstream.

Function ext4_empty_dir() doesn't correctly handle directories with
holes and crashes on bh->b_data dereference when bh is NULL. Reorganize
the loop to use 'offset' variable all the times instead of comparing
pointers to current direntry with bh->b_data pointer. Also add more
strict checking of '.' and '..' directory entries to avoid entering loop
in possibly invalid state on corrupted filesystems.

References: CVE-2019-19037
CC: stable@vger.kernel.org
Fixes: 4e19d6b65fb4 ("ext4: allow directory holes")
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191202170213.4761-2-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>