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>
---
 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 1ab79a6dec84..7e75a1936256 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)
 {
-- 
2.52.0.457.g6b5491de43-goog

Hi Sami,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 5714ca8cba5ed736f3733663c446cbee63a10a64]

url:    https://github.com/intel-lab-lkp/linux/commits/Sami-Tolvanen/bpf-crypto-Use-the-correct-destructor-kfunc-type/20260110-162850
base:   5714ca8cba5ed736f3733663c446cbee63a10a64
patch link:    https://lore.kernel.org/r/20260110082548.113748-7-samitolvanen%40google.com
patch subject: [PATCH bpf-next v5 1/4] bpf: crypto: Use the correct destructor kfunc type
config: sh-randconfig-r133-20260110 (https://download.01.org/0day-ci/archive/20260111/202601110205.4dwPV9eI-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 13.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260111/202601110205.4dwPV9eI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601110205.4dwPV9eI-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> kernel/bpf/crypto.c:264:18: sparse: sparse: symbol 'bpf_crypto_ctx_release_dtor' was not declared. Should it be static?

vim +/bpf_crypto_ctx_release_dtor +264 kernel/bpf/crypto.c

   263	
 > 264	__bpf_kfunc void bpf_crypto_ctx_release_dtor(void *ctx)
   265	{
   266		bpf_crypto_ctx_release(ctx);
   267	}
   268	CFI_NOSEAL(bpf_crypto_ctx_release_dtor);
   269	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki