tracing: Protect tracer flags with trace_types_lock (69d34da2) · Commits · 戴 / test

Seems that the tracer flags have never been protected from synchronous writes. Luckily, admins don't usually modify the tracing flags via two different tasks. But if scripts were to be used to modify them, then they could get corrupted. Move the trace_types_lock that protects against tracers changing to also protect the flags being set. Cc: stable@vger.kernel.org Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -2916,6 +2916,8 @@ static int trace_set_options(char *option)
		cmp += 2;
		}

		mutex_lock(&trace_types_lock);

		for (i = 0; trace_options[i]; i++) {
		if (strcmp(cmp, trace_options[i]) == 0) {
		set_tracer_flags(1 << i, !neg);
		@@ -2924,11 +2926,10 @@ static int trace_set_options(char *option)
		}

		/* If no option could be set, test the specific tracer options */
		if (!trace_options[i]) {
		mutex_lock(&trace_types_lock);
		if (!trace_options[i])
		ret = set_tracer_option(current_trace, cmp, neg);

		mutex_unlock(&trace_types_lock);
		}

		return ret;
		}
		@@ -4781,7 +4782,10 @@ trace_options_core_write(struct file filp, const char __user ubuf, size_t cnt,

		if (val != 0 && val != 1)
		return -EINVAL;

		mutex_lock(&trace_types_lock);
		set_tracer_flags(1 << index, val);
		mutex_unlock(&trace_types_lock);

		*ppos += cnt;

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