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Fri, 11 Sep 2026 15:04:20 -0700 (PDT) Received: from localhost ([2a03:2880:ff:45::]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-6c09690af1dsm3750011eaf.1.2026.09.11.15.04.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Sep 2026 15:04:20 -0700 (PDT) From: Amery Hung To: bpf@vger.kernel.org Cc: alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, memxor@gmail.com, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v2 02/23] bpf: Address check_func_arg() arguments by argno Date: Fri, 11 Sep 2026 15:03:54 -0700 Message-ID: <20260911220415.1396439-3-ameryhung@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260911220415.1396439-1-ameryhung@gmail.com> References: <20260911220415.1396439-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit check_func_arg() derives every argument from BPF_REG_1 + arg. That works for helpers, which have at most five arguments, but kfunc arguments beyond the fifth are passed on the stack. Switch to the argno_t addressing used by check_kfunc_args(): obtain argument state with get_func_arg_reg(), use argno for diagnostics, and call check_reg_arg() only when the argument is held in a register. This prepares check_func_arg() to be shared with kfunc verification. There is no functional change for helpers. reg_arg_name() renders their register arguments as R%d, so the updated diagnostics remain unchanged. Signed-off-by: Amery Hung --- kernel/bpf/verifier.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a45e0478f23c..d5e885435bb6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -8815,10 +8815,12 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, int insn_idx) { const struct bpf_func_proto *fn = meta->fn; - u32 regno = BPF_REG_1 + arg; - struct bpf_reg_state *reg = reg_state(env, regno); + struct bpf_func_state *caller = cur_func(env); + struct bpf_reg_state *regs = cur_regs(env); + argno_t argno = argno_from_arg(arg + 1); + struct bpf_reg_state *reg = get_func_arg_reg(caller, regs, arg); enum bpf_arg_type arg_type = fn->arg_type[arg]; - argno_t argno = argno_from_reg(regno); + int regno = reg_from_argno(argno); enum bpf_reg_type type = reg->type; u32 *arg_btf_id = NULL; u32 key_size; @@ -8827,14 +8829,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, if (arg_type == ARG_DONTCARE) return 0; - err = check_reg_arg(env, regno, SRC_OP); - if (err) - return err; + if (regno >= 0) { + err = check_reg_arg(env, regno, SRC_OP); + if (err) + return err; + } if (arg_type == ARG_ANYTHING) { - if (is_pointer_value(env, regno)) { - verbose(env, "R%d leaks addr into helper function\n", - regno); + if (__is_pointer_value(env->allow_ptr_leaks, reg)) { + verbose(env, "%s leaks addr into helper function\n", + reg_arg_name(env, argno)); return -EACCES; } return 0; @@ -8954,7 +8958,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, break; case ARG_PTR_TO_PERCPU_BTF_ID: if (!reg->btf_id) { - verbose(env, "Helper has invalid btf_id in R%d\n", regno); + verbose(env, "Helper has invalid btf_id in %s\n", reg_arg_name(env, argno)); return -EACCES; } meta->ret_btf = reg->btf; @@ -8991,7 +8995,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, * next is_mem_size argument below. */ if (arg_type & MEM_FIXED_SIZE) { - err = check_mem_reg(env, reg, argno_from_reg(regno), fn->arg_size[arg], + err = check_mem_reg(env, reg, argno, fn->arg_size[arg], arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ, meta, NULL); if (err) return err; @@ -9000,14 +9004,14 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, } break; case ARG_MEM_SIZE: - err = check_mem_size_reg(env, reg_state(env, regno - 1), reg, - argno_from_reg(regno - 1), argno, + err = check_mem_size_reg(env, get_func_arg_reg(caller, regs, arg - 1), reg, + argno_from_arg(arg), argno, fn->arg_type[arg - 1] & MEM_WRITE ? BPF_WRITE : BPF_READ, false, meta, NULL); break; case ARG_MEM_SIZE_OR_ZERO: - err = check_mem_size_reg(env, reg_state(env, regno - 1), reg, - argno_from_reg(regno - 1), argno, + err = check_mem_size_reg(env, get_func_arg_reg(caller, regs, arg - 1), reg, + argno_from_arg(arg), argno, fn->arg_type[arg - 1] & MEM_WRITE ? BPF_WRITE : BPF_READ, true, meta, NULL); break; -- 2.52.0