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bpf: Free special fields when update [lru_,]percpu_hash maps

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As [lru_,]percpu_hash maps support BPF_KPTR_{REF,PERCPU}, missing
calls to 'bpf_obj_free_fields()' in 'pcpu_copy_value()' could cause the
memory referenced by BPF_KPTR_{REF,PERCPU} fields to be held until the
map gets freed.

Fix this by calling 'bpf_obj_free_fields()' after
'copy_map_value[,_long]()' in 'pcpu_copy_value()'.

Fixes: 65334e64a4 ("bpf: Support kptrs in percpu hashmap and percpu LRU hashmap")
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20251105151407.12723-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Leon Hwang
2025-11-05 23:14:06 +08:00
committed by Alexei Starovoitov
parent 3249e8a17e
commit 6af6e49a76
1 changed files with 8 additions and 2 deletions
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10
kernel/bpf/hashtab.c
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@@ -934,15 +934,21 @@ static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
void *value, bool onallcpus)
{
void *ptr;
if (!onallcpus) {
/* copy true value_size bytes */
copy_map_value(&htab->map, this_cpu_ptr(pptr), value);
ptr = this_cpu_ptr(pptr);
copy_map_value(&htab->map, ptr, value);
bpf_obj_free_fields(htab->map.record, ptr);
} else {
u32 size = round_up(htab->map.value_size, 8);
int off = 0, cpu;
for_each_possible_cpu(cpu) {
copy_map_value_long(&htab->map, per_cpu_ptr(pptr, cpu), value + off);
ptr = per_cpu_ptr(pptr, cpu);
copy_map_value_long(&htab->map, ptr, value + off);
bpf_obj_free_fields(htab->map.record, ptr);
off += size;
}
}