From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
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@xxxxxxxxxx>
---
v3: refactor endp users to call the helper
v2: improve defensive pointer checking (endp theoretically can be null)
---
fs/xfs/libxfs/xfs_dir2.h | 2 ++
fs/xfs/libxfs/xfs_dir2_data.c | 43 +++++++++++++++++++++++------------------
fs/xfs/libxfs/xfs_dir2_sf.c | 4 +---
fs/xfs/scrub/dir.c | 38 +++++++++++++++++++++++++++++-------
fs/xfs/xfs_dir2_readdir.c | 4 +---
5 files changed, 58 insertions(+), 33 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index 1a8f2cf..388d67c 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -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__ */
diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 853d9ab..a1e30c7 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -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;
+ }
+}
diff --git a/fs/xfs/libxfs/xfs_dir2_sf.c b/fs/xfs/libxfs/xfs_dir2_sf.c
index 8500fa2..0c75a7f 100644
--- a/fs/xfs/libxfs/xfs_dir2_sf.c
+++ b/fs/xfs/libxfs/xfs_dir2_sf.c
@@ -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.
diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
index f5a0d17..50b6a26 100644
--- a/fs/xfs/scrub/dir.c
+++ b/fs/xfs/scrub/dir.c
@@ -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) {
diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
index 0c58918..b6ae359 100644
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -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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