Commit ce92d29d authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: directory scrubber must walk through data block to offset 



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: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent 638a7174

fs/xfs/libxfs/xfs_dir2.h

+2 −0
Original line number Diff line number Diff line
@@ -340,5 +340,7 @@ 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_da_geometry *geo,

		struct xfs_dir2_data_hdr *hdr);



#endif	/* __XFS_DIR2_H__ */

fs/xfs/libxfs/xfs_dir2_data.c

+24 −19
Original line number Diff line number Diff line
@@ -89,7 +89,6 @@ __xfs_dir3_data_check( 
	case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC):

		btp = xfs_dir2_block_tail_p(geo, hdr);

		lep = xfs_dir2_block_leaf_p(btp);

		endp = (char *)lep;



		/*

		 * The number of leaf entries is limited by the size of the
@@ -104,11 +103,13 @@ __xfs_dir3_data_check( 
		break;

	case cpu_to_be32(XFS_DIR3_DATA_MAGIC):

	case cpu_to_be32(XFS_DIR2_DATA_MAGIC):

		endp = (char *)hdr + geo->blksize;

		break;

	default:

		return __this_address;

	}

	endp = xfs_dir3_data_endp(geo, hdr);

	if (!endp)

		return __this_address;



	/*

	 * Account for zero bestfree entries.
@@ -546,7 +547,6 @@ xfs_dir2_data_freescan_int( 
	struct xfs_dir2_data_hdr *hdr,

	int			*loghead)

{

	xfs_dir2_block_tail_t	*btp;		/* block tail */

	xfs_dir2_data_entry_t	*dep;		/* active data entry */

	xfs_dir2_data_unused_t	*dup;		/* unused data entry */

	struct xfs_dir2_data_free *bf;
@@ -568,12 +568,7 @@ xfs_dir2_data_freescan_int( 
	 * Set up pointers.

	 */

	p = (char *)ops->data_entry_p(hdr);

	if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||

	    hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC)) {

		btp = xfs_dir2_block_tail_p(geo, hdr);

		endp = (char *)xfs_dir2_block_leaf_p(btp);

	} else

		endp = (char *)hdr + geo->blksize;

	endp = xfs_dir3_data_endp(geo, hdr);

	/*

	 * Loop over the block's entries.

	 */
@@ -786,17 +781,9 @@ xfs_dir2_data_make_free( 
	/*

	 * Figure out where the end of the data area is.

	 */

	if (hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||

	    hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC))

		endptr = (char *)hdr + args->geo->blksize;

	else {

		xfs_dir2_block_tail_t	*btp;	/* block tail */

	endptr = xfs_dir3_data_endp(args->geo, hdr);

	ASSERT(endptr != NULL);



		ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||

			hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));

		btp = xfs_dir2_block_tail_p(args->geo, hdr);

		endptr = (char *)xfs_dir2_block_leaf_p(btp);

	}

	/*

	 * If this isn't the start of the block, then back up to

	 * the previous entry and see if it's free.
@@ -1098,3 +1085,21 @@ 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_da_geometry		*geo,

	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(geo, hdr));

	case cpu_to_be32(XFS_DIR3_DATA_MAGIC):

	case cpu_to_be32(XFS_DIR2_DATA_MAGIC):

		return (char *)hdr + geo->blksize;

	default:

		return NULL;

	}

}

fs/xfs/libxfs/xfs_dir2_sf.c

+1 −3
Original line number Diff line number Diff line
@@ -156,7 +156,6 @@ xfs_dir2_block_to_sf( 
	xfs_dir2_sf_hdr_t	*sfhp)		/* shortform directory hdr */

{

	xfs_dir2_data_hdr_t	*hdr;		/* block header */

	xfs_dir2_block_tail_t	*btp;		/* block tail pointer */

	xfs_dir2_data_entry_t	*dep;		/* data entry pointer */

	xfs_inode_t		*dp;		/* incore directory inode */

	xfs_dir2_data_unused_t	*dup;		/* unused data pointer */
@@ -192,9 +191,8 @@ xfs_dir2_block_to_sf( 
	/*

	 * Set up to loop over the block's entries.

	 */

	btp = xfs_dir2_block_tail_p(args->geo, hdr);

	ptr = (char *)dp->d_ops->data_entry_p(hdr);

	endptr = (char *)xfs_dir2_block_leaf_p(btp);

	endptr = xfs_dir3_data_endp(args->geo, hdr);

	sfep = xfs_dir2_sf_firstentry(sfp);

	/*

	 * Loop over the active and unused entries.

fs/xfs/scrub/dir.c

+30 −8
Original line number Diff line number Diff line
@@ -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->m_dir_geo, 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));
@@ -363,13 +391,7 @@ xfs_scrub_directory_data_bestfree( 


	/* Make sure the bestfrees are actually the best free spaces. */

	ptr = (char *)d_ops->data_entry_p(bp->b_addr);

	if (is_block) {

		struct xfs_dir2_block_tail	*btp;



		btp = xfs_dir2_block_tail_p(mp->m_dir_geo, bp->b_addr);

		endptr = (char *)xfs_dir2_block_leaf_p(btp);

	} else

		endptr = (char *)bp->b_addr + BBTOB(bp->b_length);

	endptr = xfs_dir3_data_endp(mp->m_dir_geo, bp->b_addr);



	/* Iterate the entries, stopping when we hit or go past the end. */

	while (ptr < endptr) {

fs/xfs/xfs_dir2_readdir.c

+1 −3
Original line number Diff line number Diff line
@@ -152,7 +152,6 @@ xfs_dir2_block_getdents( 
	struct xfs_inode	*dp = args->dp;	/* incore directory inode */

	xfs_dir2_data_hdr_t	*hdr;		/* block header */

	struct xfs_buf		*bp;		/* buffer for block */

	xfs_dir2_block_tail_t	*btp;		/* block tail */

	xfs_dir2_data_entry_t	*dep;		/* block data entry */

	xfs_dir2_data_unused_t	*dup;		/* block unused entry */

	char			*endptr;	/* end of the data entries */
@@ -185,9 +184,8 @@ xfs_dir2_block_getdents( 
	/*

	 * Set up values for the loop.

	 */

	btp = xfs_dir2_block_tail_p(geo, hdr);

	ptr = (char *)dp->d_ops->data_entry_p(hdr);

	endptr = (char *)xfs_dir2_block_leaf_p(btp);

	endptr = xfs_dir3_data_endp(geo, hdr);



	/*

	 * Loop over the data portion of the block.

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