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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: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2017-02-02 15:14:00 -08:00
parent b3bf607d58
commit de14c5f541
1 changed files with 49 additions and 2 deletions
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51
fs/xfs/libxfs/xfs_dir2_node.c
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@ -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