tracing: Consider the NULL character when validating the event length

[ Upstream commit 0b6e2e22cb23105fcb171ab92f0f7516c69c8471 ]

strlen() returns a string length excluding the null byte. If the string
length equals to the maximum buffer length, the buffer will have no
space for the NULL terminating character.

This commit checks this condition and returns failure for it.

Link: https://lore.kernel.org/all/20241007144724.920954-1-leo.yan@arm.com/
Fixes: dec65d79fd26 ("tracing/probe: Check event name length correctly")
Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 0888f0644d2575f56ed2dbb90f7b0e3e82b01e7c..d2a1b7f03068558aaf74c29edc27c944060beecb 100644 (file)
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -261,7 +261,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
        if (len == 0) {
                trace_probe_log_err(offset, NO_EVENT_NAME);
                return -EINVAL;
-       } else if (len > MAX_EVENT_NAME_LEN) {
+       } else if (len >= MAX_EVENT_NAME_LEN) {
                trace_probe_log_err(offset, EVENT_TOO_LONG);
                return -EINVAL;
        }