linux-kernel - [PATCH v2] tracing: Consider the NULL character when validating the event length

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Message-Id: <20241007144724.920954-1-leo.yan@arm.com>
Date: Mon,  7 Oct 2024 15:47:24 +0100
From: Leo Yan <leo.yan@....com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Dave.Martin@....com,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Cc: Leo Yan <leo.yan@....com>
Subject: [PATCH v2] tracing: Consider the NULL character when validating the event length

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.

Fixes: dec65d79fd26 ("tracing/probe: Check event name length correctly")
Signed-off-by: Leo Yan <leo.yan@....com>
---

Changes from v1:
Refined for condition checking (Steve).

 kernel/trace/trace_probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 39877c80d6cb..16a5e368e7b7 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -276,7 +276,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 		}
 		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;
 	}
-- 
2.34.1