| Message ID | 20180115200447.GD5602@magnolia (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Mon, Jan 15, 2018 at 12:04:47PM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@oracle.com> > > In xfs_scrub_dir_rec, we must walk through the directory block entries > to arrive at the offset given by the hash structure. If we blindly > trust the hash address, we can end up midway into a directory entry and > stray outside the block. Found by lastbit fuzzing lents[3].address in > xfs/390 with KASAN enabled. > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > Reviewed-by: Brian Foster <bfoster@redhat.com> > --- > v2: improve defensive pointer checking (endp theoretically can be null) > --- > fs/xfs/libxfs/xfs_dir2.h | 1 + > fs/xfs/libxfs/xfs_dir2_data.c | 19 +++++++++++++++++++ > fs/xfs/scrub/dir.c | 30 +++++++++++++++++++++++++++++- > 3 files changed, 49 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h > index 1a8f2cf..2c77195 100644 > --- a/fs/xfs/libxfs/xfs_dir2.h > +++ b/fs/xfs/libxfs/xfs_dir2.h > @@ -340,5 +340,6 @@ xfs_dir2_leaf_tail_p(struct xfs_da_geometry *geo, struct xfs_dir2_leaf *lp) > #define XFS_READDIR_BUFSIZE (32768) > > unsigned char xfs_dir3_get_dtype(struct xfs_mount *mp, uint8_t filetype); > +void *xfs_dir3_data_endp(struct xfs_mount *mp, struct xfs_dir2_data_hdr *hdr); > > #endif /* __XFS_DIR2_H__ */ > diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c > index 853d9ab..b87db03 100644 > --- a/fs/xfs/libxfs/xfs_dir2_data.c > +++ b/fs/xfs/libxfs/xfs_dir2_data.c > @@ -1098,3 +1098,22 @@ xfs_dir2_data_use_free( > } > *needscanp = needscan; > } > + > +/* Find the end of the entry data in a data/block format dir block. */ > +void * > +xfs_dir3_data_endp( > + struct xfs_mount *mp, > + struct xfs_dir2_data_hdr *hdr) > +{ > + switch (hdr->magic) { > + case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC): > + case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC): > + return xfs_dir2_block_leaf_p( > + xfs_dir2_block_tail_p(mp->m_dir_geo, hdr)); > + case cpu_to_be32(XFS_DIR3_DATA_MAGIC): > + case cpu_to_be32(XFS_DIR2_DATA_MAGIC): > + return (char *)hdr + mp->m_dir_geo->blksize; > + default: > + return NULL; > + } > +} Ok, this pattern is used in a few places. e.g. xfs_dir2_data_make_free, __xfs_dir3_data_check and xfs_dir2_data_freescan_int, so if you're going to add a helper, at least convert all the other places there is the same code over to use it... Also, it should be passed a geo struct, not a xfs_mount. Cheers, Dave.
On Tue, Jan 16, 2018 at 08:56:48AM +1100, Dave Chinner wrote: > On Mon, Jan 15, 2018 at 12:04:47PM -0800, Darrick J. Wong wrote: > > From: Darrick J. Wong <darrick.wong@oracle.com> > > > > In xfs_scrub_dir_rec, we must walk through the directory block entries > > to arrive at the offset given by the hash structure. If we blindly > > trust the hash address, we can end up midway into a directory entry and > > stray outside the block. Found by lastbit fuzzing lents[3].address in > > xfs/390 with KASAN enabled. > > > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > > Reviewed-by: Brian Foster <bfoster@redhat.com> > > --- > > v2: improve defensive pointer checking (endp theoretically can be null) > > --- > > fs/xfs/libxfs/xfs_dir2.h | 1 + > > fs/xfs/libxfs/xfs_dir2_data.c | 19 +++++++++++++++++++ > > fs/xfs/scrub/dir.c | 30 +++++++++++++++++++++++++++++- > > 3 files changed, 49 insertions(+), 1 deletion(-) > > > > diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h > > index 1a8f2cf..2c77195 100644 > > --- a/fs/xfs/libxfs/xfs_dir2.h > > +++ b/fs/xfs/libxfs/xfs_dir2.h > > @@ -340,5 +340,6 @@ xfs_dir2_leaf_tail_p(struct xfs_da_geometry *geo, struct xfs_dir2_leaf *lp) > > #define XFS_READDIR_BUFSIZE (32768) > > > > unsigned char xfs_dir3_get_dtype(struct xfs_mount *mp, uint8_t filetype); > > +void *xfs_dir3_data_endp(struct xfs_mount *mp, struct xfs_dir2_data_hdr *hdr); > > > > #endif /* __XFS_DIR2_H__ */ > > diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c > > index 853d9ab..b87db03 100644 > > --- a/fs/xfs/libxfs/xfs_dir2_data.c > > +++ b/fs/xfs/libxfs/xfs_dir2_data.c > > @@ -1098,3 +1098,22 @@ xfs_dir2_data_use_free( > > } > > *needscanp = needscan; > > } > > + > > +/* Find the end of the entry data in a data/block format dir block. */ > > +void * > > +xfs_dir3_data_endp( > > + struct xfs_mount *mp, > > + struct xfs_dir2_data_hdr *hdr) > > +{ > > + switch (hdr->magic) { > > + case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC): > > + case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC): > > + return xfs_dir2_block_leaf_p( > > + xfs_dir2_block_tail_p(mp->m_dir_geo, hdr)); > > + case cpu_to_be32(XFS_DIR3_DATA_MAGIC): > > + case cpu_to_be32(XFS_DIR2_DATA_MAGIC): > > + return (char *)hdr + mp->m_dir_geo->blksize; > > + default: > > + return NULL; > > + } > > +} > > Ok, this pattern is used in a few places. e.g. > xfs_dir2_data_make_free, __xfs_dir3_data_check and > xfs_dir2_data_freescan_int, so if you're going to add a helper, at > least convert all the other places there is the same code over to > use it... > > Also, it should be passed a geo struct, not a xfs_mount. Ok. --D > Cheers, > > Dave. > > -- > Dave Chinner > david@fromorbit.com > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h index 1a8f2cf..2c77195 100644 --- a/fs/xfs/libxfs/xfs_dir2.h +++ b/fs/xfs/libxfs/xfs_dir2.h @@ -340,5 +340,6 @@ xfs_dir2_leaf_tail_p(struct xfs_da_geometry *geo, struct xfs_dir2_leaf *lp) #define XFS_READDIR_BUFSIZE (32768) unsigned char xfs_dir3_get_dtype(struct xfs_mount *mp, uint8_t filetype); +void *xfs_dir3_data_endp(struct xfs_mount *mp, struct xfs_dir2_data_hdr *hdr); #endif /* __XFS_DIR2_H__ */ diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c index 853d9ab..b87db03 100644 --- a/fs/xfs/libxfs/xfs_dir2_data.c +++ b/fs/xfs/libxfs/xfs_dir2_data.c @@ -1098,3 +1098,22 @@ xfs_dir2_data_use_free( } *needscanp = needscan; } + +/* Find the end of the entry data in a data/block format dir block. */ +void * +xfs_dir3_data_endp( + struct xfs_mount *mp, + struct xfs_dir2_data_hdr *hdr) +{ + switch (hdr->magic) { + case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC): + case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC): + return xfs_dir2_block_leaf_p( + xfs_dir2_block_tail_p(mp->m_dir_geo, hdr)); + case cpu_to_be32(XFS_DIR3_DATA_MAGIC): + case cpu_to_be32(XFS_DIR2_DATA_MAGIC): + return (char *)hdr + mp->m_dir_geo->blksize; + default: + return NULL; + } +} diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c index f5a0d17..106813f 100644 --- a/fs/xfs/scrub/dir.c +++ b/fs/xfs/scrub/dir.c @@ -200,6 +200,7 @@ xfs_scrub_dir_rec( struct xfs_inode *dp = ds->dargs.dp; struct xfs_dir2_data_entry *dent; struct xfs_buf *bp; + char *p, *endp; xfs_ino_t ino; xfs_dablk_t rec_bno; xfs_dir2_db_t db; @@ -239,8 +240,35 @@ xfs_scrub_dir_rec( } xfs_scrub_buffer_recheck(ds->sc, bp); - /* Retrieve the entry, sanity check it, and compare hashes. */ dent = (struct xfs_dir2_data_entry *)(((char *)bp->b_addr) + off); + + /* Make sure we got a real directory entry. */ + p = (char *)mp->m_dir_inode_ops->data_entry_p(bp->b_addr); + endp = xfs_dir3_data_endp(mp, bp->b_addr); + if (!endp) { + xfs_scrub_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + goto out_relse; + } + while (p < endp) { + struct xfs_dir2_data_entry *dep; + struct xfs_dir2_data_unused *dup; + + dup = (struct xfs_dir2_data_unused *)p; + if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) { + p += be16_to_cpu(dup->length); + continue; + } + dep = (struct xfs_dir2_data_entry *)p; + if (dep == dent) + break; + p += mp->m_dir_inode_ops->data_entsize(dep->namelen); + } + if (p >= endp) { + xfs_scrub_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno); + goto out_relse; + } + + /* Retrieve the entry, sanity check it, and compare hashes. */ ino = be64_to_cpu(dent->inumber); hash = be32_to_cpu(ent->hashval); tag = be16_to_cpup(dp->d_ops->data_entry_tag_p(dent));