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bpf: Ensure unit_size is matched with slab cache object size

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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>
This commit is contained in:
Hou Tao 2023-09-08 21:39:22 +08:00 committed by Alexei Starovoitov
parent b1d53958b6
commit c930472552
1 changed files with 31 additions and 2 deletions
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33
kernel/bpf/memalloc.c
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@ -486,6 +486,24 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
alloc_bulk(c, c->unit_size <= 256 ? 4 : 1, cpu_to_node(cpu), false);
}
static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx)
{
struct llist_node *first;
unsigned int obj_size;
first = c->free_llist.first;
if (!first)
return 0;
obj_size = ksize(first);
if (obj_size != c->unit_size) {
WARN_ONCE(1, "bpf_mem_cache[%u]: unexpected object size %u, expect %u\n",
idx, obj_size, c->unit_size);
return -EINVAL;
}
return 0;
}
/* When size != 0 bpf_mem_cache for each cpu.
* This is typical bpf hash map use case when all elements have equal size.
*
@ -496,10 +514,10 @@ static void prefill_mem_cache(struct bpf_mem_cache *c, int cpu)
int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
{
static u16 sizes[NUM_CACHES] = {96, 192, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096};
int cpu, i, err, unit_size, percpu_size = 0;
struct bpf_mem_caches *cc, __percpu *pcc;
struct bpf_mem_cache *c, __percpu *pc;
struct obj_cgroup *objcg = NULL;
int cpu, i, unit_size, percpu_size = 0;
if (size) {
pc = __alloc_percpu_gfp(sizeof(*pc), 8, GFP_KERNEL);
@ -537,6 +555,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
pcc = __alloc_percpu_gfp(sizeof(*cc), 8, GFP_KERNEL);
if (!pcc)
return -ENOMEM;
err = 0;
#ifdef CONFIG_MEMCG_KMEM
objcg = get_obj_cgroup_from_current();
#endif
@ -557,10 +576,20 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu)
if (i != bpf_mem_cache_idx(c->unit_size))
continue;
prefill_mem_cache(c, cpu);
err = check_obj_size(c, i);
if (err)
goto out;
}
}
out:
ma->caches = pcc;
return 0;
/* refill_work is either zeroed or initialized, so it is safe to
* call irq_work_sync().
*/
if (err)
bpf_mem_alloc_destroy(ma);
return err;
}
static void drain_mem_cache(struct bpf_mem_cache *c)