Re: [PATCH bpf-next 1/2] bpf: support bpf_get_func_arg() for BPF_TRACE_RAW_TP
From: bot+bpf-ci@kernel.org
Date: 2026-01-16 04:20:20
Also in:
bpf, lkml
quoted hunk ↗ jump to hunk
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7a375f608263..223e5b483bbd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c@@ -23321,8 +23321,18 @@ static int do_misc_fixups(struct bpf_verifier_env *env) /* Implement bpf_get_func_arg inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_arg) { + if (eatype == BPF_TRACE_RAW_TP) { + int nr_args; + + if (!prog->aux->attach_func_proto) + return -EINVAL; + nr_args = btf_type_vlen(prog->aux->attach_func_proto);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The attach_func_proto for raw tracepoints points to the BTF func_proto of __bpf_trace_* or btf_trace_* which has an extra "void *__data" as the first parameter. For example, a tracepoint declared with TP_PROTO(int a) results in a btf_trace_* typedef of "void (*)(void *__data, int a)" which has 2 parameters. Does btf_type_vlen() return the count including the hidden __data param? If so, a tracepoint with 1 actual argument would report nr_args=2, but the BPF context only contains 1 argument. Calling bpf_get_func_arg(ctx, 1) would pass the bounds check (1 < 2) but read out of bounds from ctx. The bpf_trace_run* functions populate args[] with only the actual tracepoint arguments (see __bpf_trace_run() in kernel/trace/bpf_trace.c), not including __data. Should nr_args be adjusted by subtracting 1 to account for the hidden first parameter?
+ /* Save nr_args to reg0 */
+ insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args);
+ } else {
+ /* Load nr_args from ctx - 8 */
+ insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
+ }[ ... ]
quoted hunk ↗ jump to hunk
@@ -23374,8 +23384,18 @@ static int do_misc_fixups(struct bpf_verifier_env *env) /* Implement get_func_arg_cnt inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && insn->imm == BPF_FUNC_get_func_arg_cnt) { + if (eatype == BPF_TRACE_RAW_TP) { + int nr_args; + + if (!prog->aux->attach_func_proto) + return -EINVAL; + nr_args = btf_type_vlen(prog->aux->attach_func_proto);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Same question here for bpf_get_func_arg_cnt() - should this subtract 1 to exclude the __data parameter from the count returned to BPF programs?
+ /* Save nr_args to reg0 */ + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, nr_args);
[ ... ] --- AI reviewed your patch. Please fix the bug or email reply why it's not a bug. See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21055137351