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Commit de14c5f5 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: verify free block header fields 



Perform basic sanity checking of the directory free block header
fields so that we avoid hanging the system on invalid data.

(Granted that just means that now we shutdown on directory write,
but that seems better than hanging...)

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent b3bf607d

fs/xfs/libxfs/xfs_dir2_node.c

+49 −2
Original line number Diff line number Diff line
@@ -155,6 +155,42 @@ const struct xfs_buf_ops xfs_dir3_free_buf_ops = { 
	.verify_write = xfs_dir3_free_write_verify,

};



/* Everything ok in the free block header? */

static bool

xfs_dir3_free_header_check(

	struct xfs_inode	*dp,

	xfs_dablk_t		fbno,

	struct xfs_buf		*bp)

{

	struct xfs_mount	*mp = dp->i_mount;

	unsigned int		firstdb;

	int			maxbests;



	maxbests = dp->d_ops->free_max_bests(mp->m_dir_geo);

	firstdb = (xfs_dir2_da_to_db(mp->m_dir_geo, fbno) -

		   xfs_dir2_byte_to_db(mp->m_dir_geo, XFS_DIR2_FREE_OFFSET)) *

			maxbests;

	if (xfs_sb_version_hascrc(&mp->m_sb)) {

		struct xfs_dir3_free_hdr *hdr3 = bp->b_addr;



		if (be32_to_cpu(hdr3->firstdb) != firstdb)

			return false;

		if (be32_to_cpu(hdr3->nvalid) > maxbests)

			return false;

		if (be32_to_cpu(hdr3->nvalid) < be32_to_cpu(hdr3->nused))

			return false;

	} else {

		struct xfs_dir2_free_hdr *hdr = bp->b_addr;



		if (be32_to_cpu(hdr->firstdb) != firstdb)

			return false;

		if (be32_to_cpu(hdr->nvalid) > maxbests)

			return false;

		if (be32_to_cpu(hdr->nvalid) < be32_to_cpu(hdr->nused))

			return false;

	}

	return true;

}



static int

__xfs_dir3_free_read(
@@ -168,11 +204,22 @@ __xfs_dir3_free_read( 


	err = xfs_da_read_buf(tp, dp, fbno, mappedbno, bpp,

				XFS_DATA_FORK, &xfs_dir3_free_buf_ops);

	if (err || !*bpp)

		return err;



	/* Check things that we can't do in the verifier. */

	if (!xfs_dir3_free_header_check(dp, fbno, *bpp)) {

		xfs_buf_ioerror(*bpp, -EFSCORRUPTED);

		xfs_verifier_error(*bpp);

		xfs_trans_brelse(tp, *bpp);

		return -EFSCORRUPTED;

	}



	/* try read returns without an error or *bpp if it lands in a hole */

	if (!err && tp && *bpp)

	if (tp)

		xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_FREE_BUF);

	return err;



	return 0;

}



int