Re: [PATCH] check: check so offset is not bigger then the leaf

David Sterba
2015-06-25T16:06:16Z

On Thu, Jun 18, 2015 at 10:16:54AM -0700, Josef Bacik wrote:
> On 06/18/2015 09:44 AM, David Sterba wrote:
> > On Thu, Jun 18, 2015 at 01:59:13AM +0200, Robert Marklund wrote:
> >> This could crash before because of dangerous dangling
> >> offset of pointer.
> >
> > That's right, this can happen. There are more btrfs_item_ptr that would
> > be good to validate that way, namely in the checker as it's most likely
> > to see corrupted data.
> >
>
> The check_block stuff should be doing this, if it isn't that's where we
> need to fix it. Thanks,

Something like that?

--- a/ctree.c
+++ b/ctree.c
@@ -521,6 +521,19 @@ btrfs_check_leaf(struct btrfs_root *root, struct btrfs_disk_key *parent_key,
goto fail;
}
}
+
+ for (i = 0; i < nritems; i++) {
+ void *tmp;
+
+ tmp = btrfs_item_ptr(buf, i, void);
+ if ((long)tmp >= BTRFS_LEAF_DATA_SIZE(root)) {
+ ret = BTRFS_TREE_BLOCK_INVALID_OFFSETS;
+ fprintf(stderr, "bad item pointer %lu\n",
+ (long)tmp);
+ goto fail;
+ }
+ }
+
return BTRFS_TREE_BLOCK_CLEAN;
fail:
if (btrfs_header_owner(buf) == BTRFS_EXTENT_TREE_OBJECTID) {
---

Compile-tested only.