[PATCH 6.18 081/752] bpf: crypto: Use the correct destructor kfunc type

Sasha Levin
2026-02-28T17:49:17Z

From: Sami Tolvanen <samitolvanen@google.com>

[ Upstream commit b40a5d724f29fc2eed23ff353808a9aae616b48a ]

With CONFIG_CFI enabled, the kernel strictly enforces that indirect
function calls use a function pointer type that matches the target
function. I ran into the following type mismatch when running BPF
self-tests:

CFI failure at bpf_obj_free_fields+0x190/0x238 (target:
bpf_crypto_ctx_release+0x0/0x94; expected type: 0xa488ebfc)
Internal error: Oops - CFI: 00000000f2008228 [#1] SMP
...

As bpf_crypto_ctx_release() is also used in BPF programs and using
a void pointer as the argument would make the verifier unhappy, add
a simple stub function with the correct type and register it as the
destructor kfunc instead.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Viktor Malik <vmalik@redhat.com>
Link: https://lore.kernel.org/r/20260110082548.113748-7-samitolvanen@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/crypto.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 83c4d9943084b..1d024fe7248ac 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -261,6 +261,12 @@ __bpf_kfunc void bpf_crypto_ctx_release(struct bpf_crypto_ctx *ctx)
call_rcu(&ctx->rcu, crypto_free_cb);
}

+__bpf_kfunc void bpf_crypto_ctx_release_dtor(void *ctx)
+{
+ bpf_crypto_ctx_release(ctx);
+}
+CFI_NOSEAL(bpf_crypto_ctx_release_dtor);
+
static int bpf_crypto_crypt(const struct bpf_crypto_ctx *ctx,
const struct bpf_dynptr_kern *src,
const struct bpf_dynptr_kern *dst,
@@ -368,7 +374,7 @@ static const struct btf_kfunc_id_set crypt_kfunc_set = {

BTF_ID_LIST(bpf_crypto_dtor_ids)
BTF_ID(struct, bpf_crypto_ctx)
-BTF_ID(func, bpf_crypto_ctx_release)
+BTF_ID(func, bpf_crypto_ctx_release_dtor)

static int __init crypto_kfunc_init(void)
{
--
2.51.0