ext4: fail ext4_iget for root directory if unallocated
authorTheodore Ts'o <tytso@mit.edu>
Fri, 30 Mar 2018 01:56:09 +0000 (21:56 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Fri, 30 Mar 2018 01:56:09 +0000 (21:56 -0400)
commit8e4b5eae5decd9dfe5a4ee369c22028f90ab4c44
treefed3ad9ebc9f07a4a2b8b02181c2cf83994c99a4
parentce3fd194fcc6fbdc00ce095a852f22df97baa401
ext4: fail ext4_iget for root directory if unallocated

If the root directory has an i_links_count of zero, then when the file
system is mounted, then when ext4_fill_super() notices the problem and
tries to call iput() the root directory in the error return path,
ext4_evict_inode() will try to free the inode on disk, before all of
the file system structures are set up, and this will result in an OOPS
caused by a NULL pointer dereference.

This issue has been assigned CVE-2018-1092.

https://bugzilla.kernel.org/show_bug.cgi?id=199179
https://bugzilla.redhat.com/show_bug.cgi?id=1560777

Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
fs/ext4/inode.c