6.6-stable review patch. If anyone has any objections, please let me know.
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From: Leon Hwang leon.hwang@linux.dev
[ Upstream commit 6af6e49a76c9af7d42eb923703e7648cb2bf401a ]
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: 65334e64a493 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/hashtab.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 8a3eadf17f785..8bac6ae1204dc 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -957,15 +957,21 @@ 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; } }