From: "Darrick J. Wong" darrick.wong@oracle.com
[ Upstream commit 46c59736d8090e602f960aeaf1c6b8292151bf38 ]
If a malicious filesystem image contains a block+ format directory wherein the directory inode's core.mode is set such that S_ISDIR(core.mode) == 0, and if there are subdirectories of the corrupted directory, an attempt to traverse up the directory tree will crash the kernel in __xfs_dir3_data_check. Running the online scrub's parent checks will tend to do this.
The crash occurs because the directory inode's d_ops get set to xfs_dir[23]_nondir_ops (it's not a directory) but the parent pointer scrubber's indiscriminate call to xfs_readdir proceeds past the ASSERT if we have non fatal asserts configured.
Fix the null pointer dereference crash in __xfs_dir3_data_check by looking for S_ISDIR or wrong d_ops; and teach the parent scrubber to bail out if it is fed a non-directory "parent".
Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Reviewed-by: Brian Foster bfoster@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- fs/xfs/libxfs/xfs_dir2_data.c | 8 ++++++++ fs/xfs/scrub/parent.c | 2 +- 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c index 8727a43115ef..700acc43289b 100644 --- a/fs/xfs/libxfs/xfs_dir2_data.c +++ b/fs/xfs/libxfs/xfs_dir2_data.c @@ -73,6 +73,14 @@ __xfs_dir3_data_check( */ ops = xfs_dir_get_ops(mp, dp);
+ /* + * If this isn't a directory, or we don't get handed the dir ops, + * something is seriously wrong. Bail out. + */ + if ((dp && !S_ISDIR(VFS_I(dp)->i_mode)) || + ops != xfs_dir_get_ops(mp, NULL)) + return __this_address; + hdr = bp->b_addr; p = (char *)ops->data_entry_p(hdr);
diff --git a/fs/xfs/scrub/parent.c b/fs/xfs/scrub/parent.c index 63a25334fc83..b4d2f8406d22 100644 --- a/fs/xfs/scrub/parent.c +++ b/fs/xfs/scrub/parent.c @@ -171,7 +171,7 @@ xfs_scrub_parent_validate( error = xfs_iget(mp, sc->tp, dnum, 0, 0, &dp); if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, 0, &error)) goto out; - if (dp == sc->ip) { + if (dp == sc->ip || !S_ISDIR(VFS_I(dp)->i_mode)) { xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0); goto out_rele; }