linux-kernel - Re: [PATCH 16/21] tracing/uprobe: Add per-probe delete from event

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Date:   Mon, 17 Jun 2019 22:16:46 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH 16/21] tracing/uprobe: Add per-probe delete from event

On Sat,  1 Jun 2019 00:19:17 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> +static bool trace_uprobe_match_command_head(struct trace_uprobe *tu,
> +					    int argc, const char **argv)
> +{
> +	char buf[MAX_ARGSTR_LEN + 1];
> +	int len;
> +
> +	if (!argc)
> +		return true;
> +
> +	len = strlen(tu->filename);
> +	if (argv[0][len] != ':' || strncmp(tu->filename, argv[0], len))

Hmm, isn't it possible that 'len' can be greater than whatever argv[0] is?

The argv[0][len] looks very dangerous to me.

Perhaps that should be changed to:

	if (!(!strncmp(tu->filename, argv[0], len) && argv[0][len] == ':'))

That way, the test of argv[0][len] will only happen if argv[0] is of length len.

-- Steve


> +		return false;
> +
> +	if (tu->ref_ctr_offset == 0)
> +		snprintf(buf, sizeof(buf), "0x%0*lx",
> +				(int)(sizeof(void *) * 2), tu->offset);
> +	else
> +		snprintf(buf, sizeof(buf), "0x%0*lx(0x%lx)",
> +				(int)(sizeof(void *) * 2), tu->offset,
> +				tu->ref_ctr_offset);
> +	if (strcmp(buf, &argv[0][len + 1]))
> +		return false;
> +
> +	argc--; argv++;
> +
> +	return trace_probe_match_command_args(&tu->tp, argc, argv);
> +}
> +