On Tue, 19 Mar 2024 10:19:09 +0300
Dan Carpenter <dan.carpen...@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
