Hello Btrfs devs,
The patch 5d4f98a28c7d: "Btrfs: Mixed back reference (FORWARD
ROLLING FORMAT CHANGE)" from Jun 10, 2009, leads to the following
warning:
fs/btrfs/relocation.c:1270 __update_reloc_root()
error: potential NULL dereference 'node'.
fs/btrfs/relocation.c
1255 static int __update_reloc_root(struct btrfs_root *root, int del)
1256 {
1257 struct rb_node *rb_node;
1258 struct mapping_node *node = NULL;
1259 struct reloc_control *rc = root->fs_info->reloc_ctl;
1260
1261 spin_lock(&rc->reloc_root_tree.lock);
1262 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1263 root->commit_root->start);
1264 if (rb_node) {
1265 node = rb_entry(rb_node, struct mapping_node, rb_node);
^^^^^^^^^^^^^^^^
Node is only non-NULL if "rb_node" is non-NULL.
1266 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1267 }
1268 spin_unlock(&rc->reloc_root_tree.lock);
1269
1270 BUG_ON((struct btrfs_root *)node->data != root);
^^^^^^^^^^
Null dereference.
1271
1272 if (!del) {
1273 spin_lock(&rc->reloc_root_tree.lock);
1274 node->bytenr = root->node->start;
^^^^^^^^^^^^
We assume "node" is non-NULL on this side of the if else statement.
1275 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1276 node->bytenr, &node->rb_node);
1277 spin_unlock(&rc->reloc_root_tree.lock);
1278 if (rb_node)
1279 backref_tree_panic(rb_node, -EEXIST,
node->bytenr);
1280 } else {
1281 spin_lock(&root->fs_info->trans_lock);
1282 list_del_init(&root->root_list);
1283 spin_unlock(&root->fs_info->trans_lock);
1284 kfree(node);
^^^^^^^^^^^
And here as well I guess.
1285 }
1286 return 0;
regards,
dan carpenter
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