BACKPORT: 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
Backport Note: As EFSCORRUPTED does not exist in 3.10, use EIO instead.
BUG=chromium:839356
TEST=None
Change-Id: Iaa2cf501cc246b23c6ba84e3dd6ad46323d581f7
Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
(cherry picked from commit 8e4b5eae5decd9dfe5a4ee369c22028f90ab4c44)
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1042606
Reviewed-by: Guenter Roeck <groeck@chromium.org>
(cherry picked from commit e05dc621c4b78012fe60989ed3ef3dee83be84aa)
Reviewed-on: https://chromium-review.googlesource.com/1055114
1 file changed
