tree 1cc09f64094ce30bd09bd67c8100f5285b726378
parent fbcc6efc92a2d5f92016bf46bef963026cbd4979
author Theodore Ts'o <tytso@mit.edu> 1522374969 -0400
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> 1525757840 +0000

UPSTREAM: ext4: fail ext4_iget for root directory if unallocated

commit 8e4b5eae5decd9dfe5a4ee369c22028f90ab4c44 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

BUG=b:79190698
TEST=trybot

Change-Id: I3da89db25e609a24ff6962032c4c8a0ef819bd08
Signed-off-by: Pradeep Sawlani <sawlani@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1045090
Reviewed-by: Guenter Roeck <groeck@chromium.org>