Btrfs: improve check_node to avoid reading corrupted nodes

We need to check items in a node to make sure that we're reading
a valid one, otherwise we could get various crashes while processing
delayed_refs.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e4c2428..92dd26e 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -546,9 +546,10 @@ static int check_tree_block_fsid(struct btrfs_fs_info *fs_info,
 }
 
 #define CORRUPT(reason, eb, root, slot)                                \
-       btrfs_crit(root->fs_info, "corrupt leaf, %s: block=%llu,"       \
-                  "root=%llu, slot=%d", reason,                        \
-              btrfs_header_bytenr(eb), root->objectid, slot)
+       btrfs_crit(root->fs_info, "corrupt %s, %s: block=%llu," \
+                  " root=%llu, slot=%d",                       \
+                  btrfs_header_level(eb) == 0 ? "leaf" : "node",\
+                  reason, btrfs_header_bytenr(eb), root->objectid, slot)
 
 static noinline int check_leaf(struct btrfs_root *root,
                               struct extent_buffer *leaf)
@@ -635,6 +636,10 @@ static noinline int check_leaf(struct btrfs_root *root,
 static int check_node(struct btrfs_root *root, struct extent_buffer *node)
 {
        unsigned long nr = btrfs_header_nritems(node);
+       struct btrfs_key key, next_key;
+       int slot;
+       u64 bytenr;
+       int ret = 0;
 
        if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(root)) {
                btrfs_crit(root->fs_info,
@@ -642,7 +647,26 @@ static int check_node(struct btrfs_root *root, struct extent_buffer *node)
                           node->start, root->objectid, nr);
                return -EIO;
        }
-       return 0;
+
+       for (slot = 0; slot < nr - 1; slot++) {
+               bytenr = btrfs_node_blockptr(node, slot);
+               btrfs_node_key_to_cpu(node, &key, slot);
+               btrfs_node_key_to_cpu(node, &next_key, slot + 1);
+
+               if (!bytenr) {
+                       CORRUPT("invalid item slot", node, root, slot);
+                       ret = -EIO;
+                       goto out;
+               }
+
+               if (btrfs_comp_cpu_keys(&key, &next_key) >= 0) {
+                       CORRUPT("bad key order", node, root, slot);
+                       ret = -EIO;
+                       goto out;
+               }
+       }
+out:
+       return ret;
 }
 
 static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio,