xfs: directory scrubber must walk through data block to offset
Source kernel commit: ce92d29ddf9908d397895c46b7c78e9db8df414d
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>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
diff --git a/libxfs/xfs_dir2.h b/libxfs/xfs_dir2.h
index 1a8f2cf..388d67c 100644
--- a/libxfs/xfs_dir2.h
+++ b/libxfs/xfs_dir2.h
@@ -340,5 +340,7 @@
#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__ */
diff --git a/libxfs/xfs_dir2_data.c b/libxfs/xfs_dir2_data.c
index 1f46115..175c119 100644
--- a/libxfs/xfs_dir2_data.c
+++ b/libxfs/xfs_dir2_data.c
@@ -86,7 +86,6 @@
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
@@ -101,11 +100,13 @@
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.
@@ -543,7 +544,6 @@
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;
@@ -565,12 +565,7 @@
* 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.
*/
@@ -783,17 +778,9 @@
/*
* 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.
@@ -1095,3 +1082,21 @@
}
*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;
+ }
+}
diff --git a/libxfs/xfs_dir2_sf.c b/libxfs/xfs_dir2_sf.c
index cf352b6..fbb9482 100644
--- a/libxfs/xfs_dir2_sf.c
+++ b/libxfs/xfs_dir2_sf.c
@@ -154,7 +154,6 @@
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 */
@@ -190,9 +189,8 @@
/*
* 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.
