On Wed, Mar 21, 2018 at 10:59:12PM -0700, Darrick J. Wong wrote:
> 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>
> ---
> v2: release buffers defensively, fix some formatting weirdness
> ---
> fs/xfs/libxfs/xfs_dir2.h | 2 +
> fs/xfs/libxfs/xfs_dir2_block.c | 49 +++++++++++++++----------
> fs/xfs/libxfs/xfs_dir2_data.c | 78 +++++++++++++++++++++++++++++++---------
> fs/xfs/libxfs/xfs_dir2_leaf.c | 6 +++
> fs/xfs/libxfs/xfs_dir2_node.c | 9 ++++-
> 5 files changed, 103 insertions(+), 41 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..e8256e2 100644
> --- a/fs/xfs/libxfs/xfs_dir2_block.c
> +++ b/fs/xfs/libxfs/xfs_dir2_block.c
...
> @@ -541,9 +545,11 @@ 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);
Still several of these broken alignments (i.e., the ones where the
'error = ...' indents the first line).
Brian
> + if (error)
> + return error;
> /*
> * Create the new data entry.
> */
> @@ -997,8 +1003,10 @@ 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 +1118,14 @@ 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 +1140,10 @@ 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 +1156,11 @@ 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 +1264,7 @@ 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..57b6c4fa 100644
> --- a/fs/xfs/libxfs/xfs_dir2_node.c
> +++ b/fs/xfs/libxfs/xfs_dir2_node.c
> @@ -1729,6 +1729,7 @@ xfs_dir2_node_addname_int(
> __be16 *bests;
> struct xfs_dir3_icfree_hdr freehdr;
> struct xfs_dir2_data_free *bf;
> + xfs_dir2_data_aoff_t aoff;
>
> dp = args->dp;
> mp = dp->i_mount;
> @@ -2023,9 +2024,13 @@ xfs_dir2_node_addname_int(
> /*
> * Mark the first part of the unused space, inuse for us.
> */
> - xfs_dir2_data_use_free(args, dbp, dup,
> - (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr), length,
> + aoff = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
> + error = xfs_dir2_data_use_free(args, dbp, dup, aoff, length,
> &needlog, &needscan);
> + if (error) {
> + xfs_trans_brelse(tp, dbp);
> + return error;
> + }
> /*
> * Fill in the new entry and log it.
> */
> --
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