netdev - [PATCH bpf-next 1/4] bpf: crypto: Use the correct destructor kfunc type

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Message-ID: <20250724223225.1481960-7-samitolvanen@google.com>
Date: Thu, 24 Jul 2025 22:32:27 +0000
From: Sami Tolvanen <samitolvanen@...gle.com>
To: bpf@...r.kernel.org
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>, Alexei Starovoitov <ast@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, Jamal Hadi Salim <jhs@...atatu.com>, 
	Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH bpf-next 1/4] bpf: crypto: Use the correct destructor kfunc type

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@...gle.com>
---
 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)
+{
+	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)
 {
-- 
2.50.1.470.g6ba607880d-goog