diff options
| author | Randy Dunlap <rdunlap@infradead.org> | 2020-12-18 21:17:16 +0100 |
|---|---|---|
| committer | Dave Kleikamp <dave.kleikamp@oracle.com> | 2020-12-18 22:23:33 +0100 |
| commit | 3bef198f1b17d1bb89260bad947ef084c0a2d1a6 (patch) | |
| tree | 16207f33943d800ae976b762f8d5710bed86a92a /fs/jfs/jfs_filsys.h | |
| parent | Merge tag 'xfs-5.11-merge-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux (diff) | |
| download | linux-3bef198f1b17d1bb89260bad947ef084c0a2d1a6.tar.xz linux-3bef198f1b17d1bb89260bad947ef084c0a2d1a6.zip | |
JFS: more checks for invalid superblock
syzbot is feeding invalid superblock data to JFS for mount testing.
JFS does not check several of the fields -- just assumes that they
are good since the JFS_MAGIC and version fields are good.
In this case (syzbot reproducer), we have s_l2bsize == 0xda0c,
pad == 0xf045, and s_state == 0x50, all of which are invalid IMO.
Having s_l2bsize == 0xda0c causes this UBSAN warning:
UBSAN: shift-out-of-bounds in fs/jfs/jfs_mount.c:373:25
shift exponent -9716 is negative
s_l2bsize can be tested for correctness. pad can be tested for non-0
and punted. s_state can be tested for its valid values and punted.
Do those 3 tests and if any of them fails, report the superblock as
invalid/corrupt and let fsck handle it.
With this patch, chkSuper() says this when JFS_DEBUG is enabled:
jfs_mount: Mount Failure: superblock is corrupt!
Mount JFS Failure: -22
jfs_mount failed w/return code = -22
The obvious problem with this method is that next week there could
be another syzbot test that uses different fields for invalid values,
this making this like a game of whack-a-mole.
syzkaller link: https://syzkaller.appspot.com/bug?extid=36315852ece4132ec193
Reported-by: syzbot+36315852ece4132ec193@syzkaller.appspotmail.com
Reported-by: kernel test robot <lkp@intel.com> # v2
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: jfs-discussion@lists.sourceforge.net
Diffstat (limited to 'fs/jfs/jfs_filsys.h')
| -rw-r--r-- | fs/jfs/jfs_filsys.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/jfs/jfs_filsys.h b/fs/jfs/jfs_filsys.h index 1e899298f7f0..b5d702df7111 100644 --- a/fs/jfs/jfs_filsys.h +++ b/fs/jfs/jfs_filsys.h @@ -268,5 +268,6 @@ * fsck() must be run to repair */ #define FM_EXTENDFS 0x00000008 /* file system extendfs() in progress */ +#define FM_STATE_MAX 0x0000000f /* max value of s_state */ #endif /* _H_JFS_FILSYS */ |