linux-kernel - [PATCH AUTOSEL 6.12 249/486] bpf: Search and add kfuncs in struct

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Message-Id: <20250505223922.2682012-249-sashal@kernel.org>
Date: Mon,  5 May 2025 18:35:25 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Amery Hung <amery.hung@...edance.com>,
	Eduard Zingerman <eddyz87@...il.com>,
	Martin KaFai Lau <martin.lau@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	daniel@...earbox.net,
	andrii@...nel.org,
	bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 6.12 249/486] bpf: Search and add kfuncs in struct_ops prologue and epilogue

From: Amery Hung <amery.hung@...edance.com>

[ Upstream commit d519594ee2445d7cd1ad51f4db4cee58f8213400 ]

Currently, add_kfunc_call() is only invoked once before the main
verification loop. Therefore, the verifier could not find the
bpf_kfunc_btf_tab of a new kfunc call which is not seen in user defined
struct_ops operators but introduced in gen_prologue or gen_epilogue
during do_misc_fixup(). Fix this by searching kfuncs in the patching
instruction buffer and add them to prog->aux->kfunc_tab.

Signed-off-by: Amery Hung <amery.hung@...edance.com>
Acked-by: Eduard Zingerman <eddyz87@...il.com>
Acked-by: Martin KaFai Lau <martin.lau@...nel.org>
Link: https://lore.kernel.org/r/20250225233545.285481-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/bpf/verifier.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 8656208aa4bbb..294fbafbeba75 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2987,6 +2987,21 @@ bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
 	return res ? &res->func_model : NULL;
 }
 
+static int add_kfunc_in_insns(struct bpf_verifier_env *env,
+			      struct bpf_insn *insn, int cnt)
+{
+	int i, ret;
+
+	for (i = 0; i < cnt; i++, insn++) {
+		if (bpf_pseudo_kfunc_call(insn)) {
+			ret = add_kfunc_call(env, insn->imm, insn->off);
+			if (ret < 0)
+				return ret;
+		}
+	}
+	return 0;
+}
+
 static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
 {
 	struct bpf_subprog_info *subprog = env->subprog_info;
@@ -19768,7 +19783,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 {
 	struct bpf_subprog_info *subprogs = env->subprog_info;
 	const struct bpf_verifier_ops *ops = env->ops;
-	int i, cnt, size, ctx_field_size, delta = 0, epilogue_cnt = 0;
+	int i, cnt, size, ctx_field_size, ret, delta = 0, epilogue_cnt = 0;
 	const int insn_cnt = env->prog->len;
 	struct bpf_insn *epilogue_buf = env->epilogue_buf;
 	struct bpf_insn *insn_buf = env->insn_buf;
@@ -19797,6 +19812,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 				return -ENOMEM;
 			env->prog = new_prog;
 			delta += cnt - 1;
+
+			ret = add_kfunc_in_insns(env, epilogue_buf, epilogue_cnt - 1);
+			if (ret < 0)
+				return ret;
 		}
 	}
 
@@ -19817,6 +19836,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 
 			env->prog = new_prog;
 			delta += cnt - 1;
+
+			ret = add_kfunc_in_insns(env, insn_buf, cnt - 1);
+			if (ret < 0)
+				return ret;
 		}
 	}
 
-- 
2.39.5