bpf: Fix map leak in HASH_OF_MAPS map (1d4e1eab) · Commits · 戴 / test

Fix HASH_OF_MAPS bug of not putting inner map pointer on bpf_map_elem_update() operation. This is due to per-cpu extra_elems optimization, which bypassed free_htab_elem() logic doing proper clean ups. Make sure that inner map is put properly in optimized case as well. Fixes: ("bpf: fix hashmap extra_elems logic") Signed-off-by:

Andrii Nakryiko <andriin@fb.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net> Acked-by:

Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200729040913.2815687-1-andriin@fb.com

kernel/bpf/hashtab.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -779,15 +779,20 @@ static void htab_elem_free_rcu(struct rcu_head *head)
		htab_elem_free(htab, l);
		}

		static void free_htab_elem(struct bpf_htab htab, struct htab_elem l)
		static void htab_put_fd_value(struct bpf_htab htab, struct htab_elem l)
		{
		struct bpf_map *map = &htab->map;
		void *ptr;

		if (map->ops->map_fd_put_ptr) {
		void *ptr = fd_htab_map_get_ptr(map, l);

		ptr = fd_htab_map_get_ptr(map, l);
		map->ops->map_fd_put_ptr(ptr);
		}
		}

		static void free_htab_elem(struct bpf_htab htab, struct htab_elem l)
		{
		htab_put_fd_value(htab, l);

		if (htab_is_prealloc(htab)) {
		__pcpu_freelist_push(&htab->freelist, &l->fnode);
		@@ -839,6 +844,7 @@ static struct htab_elem alloc_htab_elem(struct bpf_htab htab, void *key,
		*/
		pl_new = this_cpu_ptr(htab->extra_elems);
		l_new = *pl_new;
		htab_put_fd_value(htab, old_elem);
		*pl_new = old_elem;
		} else {
		struct pcpu_freelist_node *l;

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