Commit c421c125 authored by Hou Tao's avatar Hou Tao Committed by Daniel Borkmann
Browse files

bpf: Add more WARN_ON_ONCE checks for mismatched alloc and free 



There are two possible mismatched alloc and free cases in BPF memory
allocator:

1) allocate from cache X but free by cache Y with a different unit_size
2) allocate from per-cpu cache but free by kmalloc cache or vice versa

So add more WARN_ON_ONCE checks in free_bulk() and __free_by_rcu() to
spot these mismatched alloc and free early.

Signed-off-by: default avatarHou Tao <houtao1@huawei.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231021014959.3563841-1-houtao@huaweicloud.com
parent 22360fad

kernel/bpf/memalloc.c

+4 −0
Original line number Diff line number Diff line
@@ -340,6 +340,7 @@ static void free_bulk(struct bpf_mem_cache *c) 
	int cnt;



	WARN_ON_ONCE(tgt->unit_size != c->unit_size);

	WARN_ON_ONCE(tgt->percpu_size != c->percpu_size);



	do {

		inc_active(c, &flags);
@@ -365,6 +366,9 @@ static void __free_by_rcu(struct rcu_head *head) 
	struct bpf_mem_cache *tgt = c->tgt;

	struct llist_node *llnode;



	WARN_ON_ONCE(tgt->unit_size != c->unit_size);

	WARN_ON_ONCE(tgt->percpu_size != c->percpu_size);



	llnode = llist_del_all(&c->waiting_for_gp);

	if (!llnode)

		goto out;