From 4ed8b5bcfada6687baa478bf8febe891d9107118 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Wed, 5 Jul 2023 20:34:47 -0700 Subject: [PATCH] bpf: Add object leak check. The object leak check is cheap. Do it unconditionally to spot difficult races in bpf_mem_alloc. Signed-off-by: Hou Tao Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20230706033447.54696-15-alexei.starovoitov@gmail.com --- kernel/bpf/memalloc.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 17ef2e9..51d6389 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -567,8 +567,43 @@ static void drain_mem_cache(struct bpf_mem_cache *c) free_all(llist_del_all(&c->waiting_for_gp), percpu); } +static void check_mem_cache(struct bpf_mem_cache *c) +{ + WARN_ON_ONCE(!llist_empty(&c->free_by_rcu_ttrace)); + WARN_ON_ONCE(!llist_empty(&c->waiting_for_gp_ttrace)); + WARN_ON_ONCE(!llist_empty(&c->free_llist)); + WARN_ON_ONCE(!llist_empty(&c->free_llist_extra)); + WARN_ON_ONCE(!llist_empty(&c->free_by_rcu)); + WARN_ON_ONCE(!llist_empty(&c->free_llist_extra_rcu)); + WARN_ON_ONCE(!llist_empty(&c->waiting_for_gp)); +} + +static void check_leaked_objs(struct bpf_mem_alloc *ma) +{ + struct bpf_mem_caches *cc; + struct bpf_mem_cache *c; + int cpu, i; + + if (ma->cache) { + for_each_possible_cpu(cpu) { + c = per_cpu_ptr(ma->cache, cpu); + check_mem_cache(c); + } + } + if (ma->caches) { + for_each_possible_cpu(cpu) { + cc = per_cpu_ptr(ma->caches, cpu); + for (i = 0; i < NUM_CACHES; i++) { + c = &cc->cache[i]; + check_mem_cache(c); + } + } + } +} + static void free_mem_alloc_no_barrier(struct bpf_mem_alloc *ma) { + check_leaked_objs(ma); free_percpu(ma->cache); free_percpu(ma->caches); ma->cache = NULL; -- 2.7.4