diff options
| author | Theodore Ts'o <tytso@mit.edu> | 2018-03-29 21:56:09 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-24 09:34:12 +0200 |
| commit | 6b289a7c34d72212bcd5a8ab9b6a657f2f44f0ee (patch) | |
| tree | a28f2befc24019837aa8cddc2342f71515793661 /fs/ext4 | |
| parent | c636feb8ffe56f1cc1fafce87a67b1020761d24d (diff) | |
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>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/inode.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 6eaa864c05a9..340428274532 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4493,6 +4493,12 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) goto bad_inode; raw_inode = ext4_raw_inode(&iloc); + if ((ino == EXT4_ROOT_INO) && (raw_inode->i_links_count == 0)) { + EXT4_ERROR_INODE(inode, "root inode unallocated"); + ret = -EFSCORRUPTED; + goto bad_inode; + } + if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) { ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize); if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > |