Received-SPF: pass (google.com: domain of linux-kernel+bounces-153718-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
From: Daniel Thompson <daniel.thompson@linaro.org>
Date: Mon, 22 Apr 2024 17:35:58 +0100
Subject: [PATCH v2 5/7] kdb: Use format-specifiers rather than memset() for
 padding in kdb_read()
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <20240422-kgdb_read_refactor-v2-5-ed51f7d145fe@linaro.org>
References: <20240422-kgdb_read_refactor-v2-0-ed51f7d145fe@linaro.org>
In-Reply-To: <20240422-kgdb_read_refactor-v2-0-ed51f7d145fe@linaro.org>
To: Jason Wessel <jason.wessel@windriver.com>, 
 Douglas Anderson <dianders@chromium.org>
Cc: kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org, 
 Daniel Thompson <daniel.thompson@linaro.org>, stable@vger.kernel.org

Currently when the current line should be removed from the display
kdb_read() uses memset() to fill a temporary buffer with spaces.
The problem is not that this could be trivially implemented using a
format string rather than open coding it. The real problem is that
it is possible, on systems with a long kdb_prompt_str, to write pas
the end of the tmpbuffer.

Happily, as mentioned above, this can be trivially implemented using a
format string. Make it so!

Cc: stable@vger.kernel.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 kernel/debug/kdb/kdb_io.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index f167894b11b8e..2cd17313fe652 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -299,11 +299,9 @@ static char *kdb_read(char *buffer, size_t bufsize)
 		break;
 	case 14: /* Down */
 	case 16: /* Up */
-		memset(tmpbuffer, ' ',
-		       strlen(kdb_prompt_str) + (lastchar-buffer));
-		*(tmpbuffer+strlen(kdb_prompt_str) +
-		  (lastchar-buffer)) = '\0';
-		kdb_printf("\r%s\r", tmpbuffer);
+		kdb_printf("\r%*c\r",
+			   (int)(strlen(kdb_prompt_str) + (lastchar - buffer)),
+			   ' ');
 		*lastchar = (char)key;
 		*(lastchar+1) = '\0';
 		return lastchar;

-- 
2.43.0