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SubjectRe: [RFC PATCH tracing/kprobes 4/5] perf: Support perf kprobe command for kprobe-event setup helper
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On Fri, 2009-09-25 at 12:15 -0700, Masami Hiramatsu wrote:

> +
> +#define MAX_CMDLEN 256
> +
> +static int synthesize_probepoint(struct probe_point *pp)
> +{
> + char *buf;
> + int i, len, ret;
> + pp->probes[0] = buf = (char *)calloc(MAX_CMDLEN, sizeof(char));
> + len = snprintf(buf, MAX_CMDLEN, "%s+%d", pp->function, pp->offset);

What happens if func and offset is too big for MAX_CMDLEN?

> + for (i = 0; i < pp->nr_args; i++) {

Can you have a case where pp->nr_args == 0?

> + ret = snprintf(&buf[len], MAX_CMDLEN - len, " %s",
> + pp->args[i]);
> + if (ret <= 0 || ret >= MAX_CMDLEN - len) {
> + free(pp->probes[0]);
> + return -E2BIG;
> + }
> + len += ret;
> + }
> + return pp->found = 1;
> +}
> +
> +int cmd_kprobe(int argc, const char **argv, const char *prefix __used)
> +{
> + int i, j, fd, ret, need_dwarf = 0;
> + struct probe_point *pp;
> + char buf[MAX_CMDLEN];
> +
> + argc = parse_options(argc, argv, options, kprobe_usage,
> + PARSE_OPT_STOP_AT_NON_OPTION);
> + if (argc || session.nr_probe == 0)
> + usage_with_options(kprobe_usage, options);
> +
> + /* Synthesize return probes */
> + for (j = 0; j < session.nr_probe; j++) {
> + if (session.events[j][0] != 'r') {
> + need_dwarf = 1;
> + continue;
> + }
> + ret = synthesize_probepoint(&session.probes[j]);
> + if (ret < 0)
> + semantic_error("probe point is too long.");

If we have no args but the func and offset is too big, then this does
not catch it. But this depends on if we can have no args.

-- Steve

> + }
> +
>



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