From: Steven Rostedt <rostedt@goodmis.org>
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [bug report] tracing/probes: Support $argN in return probe (kprobe and fprobe)
Date: Tue, 19 Mar 2024 10:10:00 -0400 [thread overview]
Message-ID: <20240319101000.4dbe0cc5@gandalf.local.home> (raw)
In-Reply-To: <b010488e-68aa-407c-add0-3e059254aaa0@moroto.mountain>
On Tue, 19 Mar 2024 10:19:09 +0300
Dan Carpenter <dan.carpenter@linaro.org> wrote:
> Hello Masami Hiramatsu (Google),
>
> Commit 25f00e40ce79 ("tracing/probes: Support $argN in return probe
> (kprobe and fprobe)") from Mar 4, 2024 (linux-next), leads to the
> following Smatch static checker warning:
>
> kernel/trace/trace_probe.c:856 store_trace_entry_data()
> error: uninitialized symbol 'val'.
>
> kernel/trace/trace_probe.c
> 846 return;
> 847
> 848 for (i = 0; i < earg->size; i++) {
> 849 struct fetch_insn *code = &earg->code[i];
> 850
> 851 switch (code->op) {
> 852 case FETCH_OP_ARG:
> 853 val = regs_get_kernel_argument(regs, code->param);
> 854 break;
> 855 case FETCH_OP_ST_EDATA:
> --> 856 *(unsigned long *)((unsigned long)edata + code->offset) = val;
>
> Probably the earg->code[i] always has FETCH_OP_ARG before
> FETCH_OP_ST_EDATA but Smatch isn't smart enough to figure that out...
Looks that way:
case FETCH_OP_END:
earg->code[i].op = FETCH_OP_ARG;
earg->code[i].param = argnum;
earg->code[i + 1].op = FETCH_OP_ST_EDATA;
earg->code[i + 1].offset = offset;
return offset;
But probably should still initialize val to zero or have a WARN_ON() if
that doesn't happen.
-- Steve
>
> 857 break;
> 858 case FETCH_OP_END:
> 859 goto end;
> 860 default:
> 861 break;
> 862 }
> 863 }
> 864 end:
> 865 return;
> 866 }
>
> regards,
> dan carpenter
next prev parent reply other threads:[~2024-03-19 14:07 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-19 7:19 [bug report] tracing/probes: Support $argN in return probe (kprobe and fprobe) Dan Carpenter
2024-03-19 14:10 ` Steven Rostedt [this message]
2024-03-19 14:39 ` Dan Carpenter
2024-03-20 3:44 ` Masami Hiramatsu
2024-03-20 13:22 ` Steven Rostedt
2024-03-20 8:10 ` [PATCH] tracing: probes: Fix to zero initialize a local variable Masami Hiramatsu (Google)
2024-03-20 13:26 ` Steven Rostedt
2024-03-20 13:27 ` Steven Rostedt
2024-03-20 22:56 ` Masami Hiramatsu
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