From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Abort an dir/attr btree operation if the attr btree has obvious problems
like loops back to the root or pointers don't point down the tree.
Found by fuzzing btree[0].before to zero in xfs/402, which livelocks on
the cycle in the attr btree.
Apply the same checks to xfs_da3_node_lookup_int.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_da_btree.c | 22 +++++++++++++++++++++-
fs/xfs/xfs_attr_list.c | 20 ++++++++++++++++++++
2 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 6d43358..6516115 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -1466,6 +1466,7 @@ xfs_da3_node_lookup_int(
int max;
int error;
int retval;
+ unsigned int expected_level = 0;
struct xfs_inode *dp = state->args->dp;
args = state->args;
@@ -1474,7 +1475,7 @@ xfs_da3_node_lookup_int(
* Descend thru the B-tree searching each level for the right
* node to use, until the right hashval is found.
*/
- blkno = (args->whichfork == XFS_DATA_FORK)? args->geo->leafblk : 0;
+ blkno = args->geo->leafblk;
for (blk = &state->path.blk[0], state->path.active = 1;
state->path.active <= XFS_DA_NODE_MAXDEPTH;
blk++, state->path.active++) {
@@ -1517,6 +1518,18 @@ xfs_da3_node_lookup_int(
dp->d_ops->node_hdr_from_disk(&nodehdr, node);
btree = dp->d_ops->node_tree_p(node);
+ /* Tree taller than we can handle; bail out! */
+ if (nodehdr.level >= XFS_DA_NODE_MAXDEPTH)
+ return -EFSCORRUPTED;
+
+ /* Check the level from the root. */
+ if (blkno == args->geo->leafblk)
+ expected_level = nodehdr.level - 1;
+ else if (expected_level != nodehdr.level)
+ return -EFSCORRUPTED;
+ else
+ expected_level--;
+
max = nodehdr.count;
blk->hashval = be32_to_cpu(btree[max - 1].hashval);
@@ -1562,8 +1575,15 @@ xfs_da3_node_lookup_int(
blk->index = probe;
blkno = be32_to_cpu(btree[probe].before);
}
+
+ /* We can't point back to the root. */
+ if (blkno == args->geo->leafblk)
+ return -EFSCORRUPTED;
}
+ if (expected_level != 0)
+ return -EFSCORRUPTED;
+
/*
* A leaf block that ends in the hashval that we are interested in
* (final hashval == search hashval) means that the next block may
diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c
index 021ec5a..a360310 100644
--- a/fs/xfs/xfs_attr_list.c
+++ b/fs/xfs/xfs_attr_list.c
@@ -223,6 +223,7 @@ xfs_attr_node_list_lookup(
struct xfs_buf *bp;
int i;
int error = 0;
+ unsigned int expected_level = 0;
uint16_t magic;
ASSERT(*pbp == NULL);
@@ -246,6 +247,18 @@ xfs_attr_node_list_lookup(
dp->d_ops->node_hdr_from_disk(&nodehdr, node);
+ /* Tree taller than we can handle; bail out! */
+ if (nodehdr.level >= XFS_DA_NODE_MAXDEPTH)
+ goto out_corruptbuf;
+
+ /* Check the level from the root node. */
+ if (cursor->blkno == 0)
+ expected_level = nodehdr.level - 1;
+ else if (expected_level != nodehdr.level)
+ goto out_corruptbuf;
+ else
+ expected_level--;
+
btree = dp->d_ops->node_tree_p(node);
for (i = 0; i < nodehdr.count; btree++, i++) {
if (cursor->hashval <= be32_to_cpu(btree->hashval)) {
@@ -259,8 +272,15 @@ xfs_attr_node_list_lookup(
if (i == nodehdr.count)
return 0;
+
+ /* We can't point back to the root. */
+ if (cursor->blkno == 0)
+ return -EFSCORRUPTED;
}
+ if (expected_level != 0)
+ goto out_corruptbuf;
+
*pbp = bp;
return 0;
--
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