From: Steven Rostedt <rostedt@goodmis.org>
Date: Fri, 4 Apr 2025 01:06:37 +0000 (-0400)
Subject: tracing: Always use memcpy() in histogram add_to_key()
X-Git-Tag: v6.16-rc1~121^2~30
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=872a0d90c1297a560b0fbee219dc5ef6eda9bcb4;p=linux-block.git

tracing: Always use memcpy() in histogram add_to_key()

The add_to_key() function tests if the key is a string or some data. If
it's a string it does some further calculations of the string size (still
truncating it to the max size it can be), and calls strncpy().

If the key isn't as string it calls memcpy(). The interesting point is
that both use the exact same parameters:

                strncpy(compound_key + key_field->offset, (char *)key, size);
        } else
                memcpy(compound_key + key_field->offset, key, size);

As strncpy() is being used simply as a memcpy() for a string, and since
strncpy() is deprecated, just call memcpy() for both memory and string
keys.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/20250403210637.1c477d4a@gandalf.local.home
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1260c23cfa5f..e139b58c3a43 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -5224,10 +5224,8 @@ static inline void add_to_key(char *compound_key, void *key,
 		/* ensure NULL-termination */
 		if (size > key_field->size - 1)
 			size = key_field->size - 1;
-
-		strncpy(compound_key + key_field->offset, (char *)key, size);
-	} else
-		memcpy(compound_key + key_field->offset, key, size);
+	}
+	memcpy(compound_key + key_field->offset, key, size);
 }
 
 static void