In the Linux kernel, the following vulnerability has been resolved:
btrfs: free mapping node on duplicate reloc root insert
__add_reloc_root() allocates a mapping_node before inserting it into rc->reloc_root_tree. If rb_simple_insert() finds an existing entry, it returns the existing rb_node and leaves the newly allocated node unlinked.
The error path then returns -EEXIST without freeing the new node. Since the node was never inserted into reloc_root_tree, the later cleanup in put_reloc_control() cannot find it either.
Free the newly allocated node before returning -EEXIST.
The callers currently assert that -EEXIST should not happen, so this is a defensive cleanup for an unexpected duplicate insert path. If the path is ever reached, the local allocation should still be released.
References
- https://git.kernel.org/stable/c/14a8be9428435ee17f17fae7991215c246b7fd43
- https://git.kernel.org/stable/c/6a8269b6459ed870a8156c106a0f597383907872
- https://git.kernel.org/stable/c/797dc567146c7e3c4f8d9680e4fbc76e0a6d9151
- https://git.kernel.org/stable/c/92bedc0455552b42ada1a1f42b0e3a8593cdfccc
- https://git.kernel.org/stable/c/ae0629ff9ccb836416ada129f4edc7efea6eaaad