From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
In xfs_dir2_data_use_free, we examine on-disk metadata and ASSERT if
it doesn't make sense. Since a carefully crafted fuzzed image can cause
the kernel to crash after blowing a bunch of assertions, let's move
those checks into a validator function and rig everything up to return
EFSCORRUPTED to userspace. Found by lastbit fuzzing ltail.bestcount via
xfs/391.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_dir2.h | 2 +
fs/xfs/libxfs/xfs_dir2_block.c | 38 ++++++++++++-------
fs/xfs/libxfs/xfs_dir2_data.c | 78 +++++++++++++++++++++++++++++++---------
fs/xfs/libxfs/xfs_dir2_leaf.c | 6 +++
fs/xfs/libxfs/xfs_dir2_node.c | 4 ++
5 files changed, 93 insertions(+), 35 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index 388d67c..989e95a 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -173,7 +173,7 @@ extern void xfs_dir2_data_log_unused(struct xfs_da_args *args,
extern void xfs_dir2_data_make_free(struct xfs_da_args *args,
struct xfs_buf *bp, xfs_dir2_data_aoff_t offset,
xfs_dir2_data_aoff_t len, int *needlogp, int *needscanp);
-extern void xfs_dir2_data_use_free(struct xfs_da_args *args,
+extern int xfs_dir2_data_use_free(struct xfs_da_args *args,
struct xfs_buf *bp, struct xfs_dir2_data_unused *dup,
xfs_dir2_data_aoff_t offset, xfs_dir2_data_aoff_t len,
int *needlogp, int *needscanp);
diff --git a/fs/xfs/libxfs/xfs_dir2_block.c b/fs/xfs/libxfs/xfs_dir2_block.c
index 2da86a3..5726402 100644
--- a/fs/xfs/libxfs/xfs_dir2_block.c
+++ b/fs/xfs/libxfs/xfs_dir2_block.c
@@ -454,12 +454,15 @@ xfs_dir2_block_addname(
/*
* Mark the space needed for the new leaf entry, now in use.
*/
- xfs_dir2_data_use_free(args, bp, enddup,
+ error = xfs_dir2_data_use_free(args, bp, enddup,
(xfs_dir2_data_aoff_t)
((char *)enddup - (char *)hdr + be16_to_cpu(enddup->length) -
sizeof(*blp)),
(xfs_dir2_data_aoff_t)sizeof(*blp),
&needlog, &needscan);
+ if (error)
+ return error;
+
/*
* Update the tail (entry count).
*/
@@ -541,9 +544,11 @@ xfs_dir2_block_addname(
/*
* Mark space for the data entry used.
*/
- xfs_dir2_data_use_free(args, bp, dup,
+ error = xfs_dir2_data_use_free(args, bp, dup,
(xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr),
(xfs_dir2_data_aoff_t)len, &needlog, &needscan);
+ if (error)
+ return error;
/*
* Create the new data entry.
*/
@@ -997,8 +1002,10 @@ xfs_dir2_leaf_to_block(
/*
* Use up the space at the end of the block (blp/btp).
*/
- xfs_dir2_data_use_free(args, dbp, dup, args->geo->blksize - size, size,
- &needlog, &needscan);
+ error = xfs_dir2_data_use_free(args, dbp, dup,
+ args->geo->blksize - size, size, &needlog, &needscan);
+ if (error)
+ return error;
/*
* Initialize the block tail.
*/
@@ -1110,18 +1117,14 @@ xfs_dir2_sf_to_block(
* Add block 0 to the inode.
*/
error = xfs_dir2_grow_inode(args, XFS_DIR2_DATA_SPACE, &blkno);
- if (error) {
- kmem_free(sfp);
- return error;
- }
+ if (error)
+ goto out_free;
/*
* Initialize the data block, then convert it to block format.
*/
error = xfs_dir3_data_init(args, blkno, &bp);
- if (error) {
- kmem_free(sfp);
- return error;
- }
+ if (error)
+ goto out_free;
xfs_dir3_block_init(mp, tp, bp, dp);
hdr = bp->b_addr;
@@ -1136,8 +1139,10 @@ xfs_dir2_sf_to_block(
*/
dup = dp->d_ops->data_unused_p(hdr);
needlog = needscan = 0;
- xfs_dir2_data_use_free(args, bp, dup, args->geo->blksize - i,
+ error = xfs_dir2_data_use_free(args, bp, dup, args->geo->blksize - i,
i, &needlog, &needscan);
+ if (error)
+ goto out_free;
ASSERT(needscan == 0);
/*
* Fill in the tail.
@@ -1150,9 +1155,11 @@ xfs_dir2_sf_to_block(
/*
* Remove the freespace, we'll manage it.
*/
- xfs_dir2_data_use_free(args, bp, dup,
+ error = xfs_dir2_data_use_free(args, bp, dup,
(xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr),
be16_to_cpu(dup->length), &needlog, &needscan);
+ if (error)
+ goto out_free;
/*
* Create entry for .
*/
@@ -1256,4 +1263,7 @@ xfs_dir2_sf_to_block(
xfs_dir2_block_log_tail(tp, bp);
xfs_dir3_data_check(dp, bp);
return 0;
+out_free:
+ kmem_free(sfp);
+ return error;
}
diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 9202794..167503d 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -932,10 +932,51 @@ xfs_dir2_data_make_free(
*needscanp = needscan;
}
+/* Check our free data for obvious signs of corruption. */
+static inline xfs_failaddr_t
+xfs_dir2_data_check_free(
+ struct xfs_dir2_data_hdr *hdr,
+ struct xfs_dir2_data_unused *dup,
+ xfs_dir2_data_aoff_t offset,
+ xfs_dir2_data_aoff_t len)
+{
+ if (hdr->magic != cpu_to_be32(XFS_DIR2_DATA_MAGIC) &&
+ hdr->magic != cpu_to_be32(XFS_DIR3_DATA_MAGIC) &&
+ hdr->magic != cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) &&
+ hdr->magic != cpu_to_be32(XFS_DIR3_BLOCK_MAGIC))
+ return __this_address;
+ if (be16_to_cpu(dup->freetag) != XFS_DIR2_DATA_FREE_TAG)
+ return __this_address;
+ if (offset < (char *)dup - (char *)hdr)
+ return __this_address;
+ if (offset + len > (char *)dup + be16_to_cpu(dup->length) - (char *)hdr)
+ return __this_address;
+ if ((char *)dup - (char *)hdr !=
+ be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)))
+ return __this_address;
+ return NULL;
+}
+
+/* Sanity-check a new bestfree entry. */
+static inline xfs_failaddr_t
+xfs_dir2_data_check_new_free(
+ struct xfs_dir2_data_hdr *hdr,
+ struct xfs_dir2_data_free *dfp,
+ struct xfs_dir2_data_unused *newdup)
+{
+ if (dfp == NULL)
+ return __this_address;
+ if (dfp->length != newdup->length)
+ return __this_address;
+ if (be16_to_cpu(dfp->offset) != (char *)newdup - (char *)hdr)
+ return __this_address;
+ return NULL;
+}
+
/*
* Take a byte range out of an existing unused space and make it un-free.
*/
-void
+int
xfs_dir2_data_use_free(
struct xfs_da_args *args,
struct xfs_buf *bp,
@@ -947,23 +988,19 @@ xfs_dir2_data_use_free(
{
xfs_dir2_data_hdr_t *hdr; /* data block header */
xfs_dir2_data_free_t *dfp; /* bestfree pointer */
+ xfs_dir2_data_unused_t *newdup; /* new unused entry */
+ xfs_dir2_data_unused_t *newdup2; /* another new unused entry */
+ struct xfs_dir2_data_free *bf;
+ xfs_failaddr_t fa;
int matchback; /* matches end of freespace */
int matchfront; /* matches start of freespace */
int needscan; /* need to regen bestfree */
- xfs_dir2_data_unused_t *newdup; /* new unused entry */
- xfs_dir2_data_unused_t *newdup2; /* another new unused entry */
int oldlen; /* old unused entry's length */
- struct xfs_dir2_data_free *bf;
hdr = bp->b_addr;
- ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
- hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
- hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
- hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));
- ASSERT(be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG);
- ASSERT(offset >= (char *)dup - (char *)hdr);
- ASSERT(offset + len <= (char *)dup + be16_to_cpu(dup->length) - (char *)hdr);
- ASSERT((char *)dup - (char *)hdr == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
+ fa = xfs_dir2_data_check_free(hdr, dup, offset, len);
+ if (fa)
+ goto corrupt;
/*
* Look up the entry in the bestfree table.
*/
@@ -1008,9 +1045,9 @@ xfs_dir2_data_use_free(
xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
dfp = xfs_dir2_data_freeinsert(hdr, bf, newdup,
needlogp);
- ASSERT(dfp != NULL);
- ASSERT(dfp->length == newdup->length);
- ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
+ fa = xfs_dir2_data_check_new_free(hdr, dfp, newdup);
+ if (fa)
+ goto corrupt;
/*
* If we got inserted at the last slot,
* that means we don't know if there was a better
@@ -1036,9 +1073,9 @@ xfs_dir2_data_use_free(
xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
dfp = xfs_dir2_data_freeinsert(hdr, bf, newdup,
needlogp);
- ASSERT(dfp != NULL);
- ASSERT(dfp->length == newdup->length);
- ASSERT(be16_to_cpu(dfp->offset) == (char *)newdup - (char *)hdr);
+ fa = xfs_dir2_data_check_new_free(hdr, dfp, newdup);
+ if (fa)
+ goto corrupt;
/*
* If we got inserted at the last slot,
* that means we don't know if there was a better
@@ -1084,6 +1121,11 @@ xfs_dir2_data_use_free(
}
}
*needscanp = needscan;
+ return 0;
+corrupt:
+ xfs_corruption_error(__func__, XFS_ERRLEVEL_LOW, args->dp->i_mount,
+ hdr, __FILE__, __LINE__, fa);
+ return -EFSCORRUPTED;
}
/* Find the end of the entry data in a data/block format dir block. */
diff --git a/fs/xfs/libxfs/xfs_dir2_leaf.c b/fs/xfs/libxfs/xfs_dir2_leaf.c
index d61d52d..f746921 100644
--- a/fs/xfs/libxfs/xfs_dir2_leaf.c
+++ b/fs/xfs/libxfs/xfs_dir2_leaf.c
@@ -877,9 +877,13 @@ xfs_dir2_leaf_addname(
/*
* Mark the initial part of our freespace in use for the new entry.
*/
- xfs_dir2_data_use_free(args, dbp, dup,
+ error = xfs_dir2_data_use_free(args, dbp, dup,
(xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr), length,
&needlog, &needscan);
+ if (error) {
+ xfs_trans_brelse(tp, lbp);
+ return error;
+ }
/*
* Initialize our new entry (at last).
*/
diff --git a/fs/xfs/libxfs/xfs_dir2_node.c b/fs/xfs/libxfs/xfs_dir2_node.c
index 0839ffe..641b352 100644
--- a/fs/xfs/libxfs/xfs_dir2_node.c
+++ b/fs/xfs/libxfs/xfs_dir2_node.c
@@ -2023,9 +2023,11 @@ xfs_dir2_node_addname_int(
/*
* Mark the first part of the unused space, inuse for us.
*/
- xfs_dir2_data_use_free(args, dbp, dup,
+ error = xfs_dir2_data_use_free(args, dbp, dup,
(xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr), length,
&needlog, &needscan);
+ if (error)
+ return error;
/*
* Fill in the new entry and log it.
*/
--
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