perf/core: Fix perf_uprobe_init()

Similarly to the uprobe PMU fix in perf_kprobe_init(), fix error
handling in perf_uprobe_init() as well.
Reported-by: 范龙飞 <long7573@126.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: e12f03d7 ("perf/core: Implement the 'perf_kprobe' PMU")
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/trace/trace_event_perf.c

@@ -302,6 +302,8 @@ int perf_uprobe_init(struct perf_event *p_event, bool is_retprobe)
 		return -ENOMEM;
 	ret = strncpy_from_user(
 		path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
+	if (ret == PATH_MAX)
+		return -E2BIG;
 	if (ret < 0)
 		goto out;
 	if (path[0] == '\0') {