Commit 6f05dcab authored Jun 06, 2023 by sunliming Committed by Steven Rostedt (Google) Jun 14, 2023

tracing/user_events: Fix the incorrect trace record for empty arguments events

The user_events support events that has empty arguments. But the trace event
is discarded and not really committed when the arguments is empty. Fix this
by not attempting to copy in zero-length data.

Link: https://lkml.kernel.org/r/20230606062027.1008398-2-sunliming@kylinos.cn

Acked-by: Beau Belgrave <beaub@linux.microsoft.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: sunliming <sunliming@kylinos.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

parent e70bb54d

kernel/trace/trace_events_user.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1432,7 +1432,7 @@ static void user_event_ftrace(struct user_event user, struct iov_iter i,
		if (unlikely(!entry))
		return;

		if (unlikely(!copy_nofault(entry + 1, i->count, i)))
		if (unlikely(i->count != 0 && !copy_nofault(entry + 1, i->count, i)))
		goto discard;

		if (!list_empty(&user->validators) &&
		@@ -1473,7 +1473,7 @@ static void user_event_perf(struct user_event user, struct iov_iter i,

		perf_fetch_caller_regs(regs);

		if (unlikely(!copy_nofault(perf_entry + 1, i->count, i)))
		if (unlikely(i->count != 0 && !copy_nofault(perf_entry + 1, i->count, i)))
		goto discard;

		if (!list_empty(&user->validators) &&