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bpf: Add object leak check.

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The object leak check is cheap. Do it unconditionally to spot difficult races
in bpf_mem_alloc.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230706033447.54696-15-alexei.starovoitov@gmail.com
This commit is contained in:
Hou Tao 2023-07-05 20:34:47 -07:00 committed by Daniel Borkmann
parent 8e07bb9ebc
commit 4ed8b5bcfa
1 changed files with 35 additions and 0 deletions
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35
kernel/bpf/memalloc.c
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@ -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;