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xfs: directory scrubber must walk through data block to offset

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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: Dave Chinner <dchinner@redhat.com>
This commit is contained in:
Darrick J. Wong
2018-01-16 18:54:12 -08:00
parent 638a717489
commit ce92d29ddf
5 changed files with 58 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
fs/xfs/libxfs/xfs_dir2_data.c
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@ -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;
}
}