On 7/24/25 3:32 PM, Sami Tolvanen wrote:
With CONFIG_CFI_CLANG 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@xxxxxxxxxx>
---
kernel/bpf/crypto.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c
index 94854cd9c4cc..b703b1d1c282 100644
--- a/kernel/bpf/crypto.c
+++ b/kernel/bpf/crypto.c
@@ -261,6 +261,11 @@ __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(void *ctx)
We are not really creating a kfunc here. The function is merely
to be used for destructor. So you can replace '__bpf_kfunc' with
'__used __retain'.
+{
+ bpf_crypto_ctx_release(ctx);
+}
+
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 +373,7 @@ 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)
static int __init crypto_kfunc_init(void)
{
