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bpf: Ensure unit_size is matched with slab cache object size
Add extra check in bpf_mem_alloc_init() to ensure the unit_size of bpf_mem_cache is matched with the object_size of underlying slab cache. If these two sizes are unmatched, print a warning once and return -EINVAL in bpf_mem_alloc_init(), so the mismatch can be found early and the potential issue can be prevented. Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20230908133923.2675053-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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c930472552
@ -486,6 +486,24 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
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alloc_bulk(c, c->unit_size <= 256 ? 4 : 1, cpu_to_node(cpu), false);
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}
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static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx)
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{
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struct llist_node *first;
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unsigned int obj_size;
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first = c->free_llist.first;
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if (!first)
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return 0;
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obj_size = ksize(first);
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if (obj_size != c->unit_size) {
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WARN_ONCE(1, "bpf_mem_cache[%u]: unexpected object size %u, expect %u\n",
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idx, obj_size, c->unit_size);
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return -EINVAL;
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}
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return 0;
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}
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/* When size != 0 bpf_mem_cache for each cpu.
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* This is typical bpf hash map use case when all elements have equal size.
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*
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@ -496,10 +514,10 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
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int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
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{
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static u16 sizes[NUM_CACHES] = {96, 192, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096};
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int cpu, i, err, unit_size, percpu_size = 0;
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struct bpf_mem_caches *cc, __percpu *pcc;
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struct bpf_mem_cache *c, __percpu *pc;
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struct obj_cgroup *objcg = NULL;
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int cpu, i, unit_size, percpu_size = 0;
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if (size) {
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pc = __alloc_percpu_gfp(sizeof(*pc), 8, GFP_KERNEL);
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@ -537,6 +555,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
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pcc = __alloc_percpu_gfp(sizeof(*cc), 8, GFP_KERNEL);
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if (!pcc)
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return -ENOMEM;
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err = 0;
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#ifdef CONFIG_MEMCG_KMEM
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objcg = get_obj_cgroup_from_current();
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#endif
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@ -557,10 +576,20 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
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if (i != bpf_mem_cache_idx(c->unit_size))
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continue;
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prefill_mem_cache(c, cpu);
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err = check_obj_size(c, i);
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if (err)
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goto out;
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}
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}
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out:
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ma->caches = pcc;
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return 0;
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/* refill_work is either zeroed or initialized, so it is safe to
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* call irq_work_sync().
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*/
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if (err)
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bpf_mem_alloc_destroy(ma);
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return err;
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}
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static void drain_mem_cache(struct bpf_mem_cache *c)
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