linux-kernel - [PATCH v2] kdb: Fix bound check compiler warning

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Date:   Mon, 13 May 2019 16:57:20 +0800
From:   Wenlin Kang <wenlin.kang@...driver.com>
To:     <jason.wessel@...driver.com>, <daniel.thompson@...aro.org>,
        <prarit@...hat.com>
CC:     <kgdb-bugreport@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] kdb: Fix bound check compiler warning

The strncpy() function may leave the destination string buffer
unterminated, better use strscpy() instead.

This fixes the following warning with gcc 8.2:

kernel/debug/kdb/kdb_io.c: In function 'kdb_getstr':
kernel/debug/kdb/kdb_io.c:449:3: warning: 'strncpy' specified bound 256 equals destination size [-Wstringop-truncation]
   strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Wenlin Kang <wenlin.kang@...driver.com>
---
 kernel/debug/kdb/kdb_io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 6a4b414..3a5184e 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -446,7 +446,7 @@ static char *kdb_read(char *buffer, size_t bufsize)
 char *kdb_getstr(char *buffer, size_t bufsize, const char *prompt)
 {
 	if (prompt && kdb_prompt_str != prompt)
-		strncpy(kdb_prompt_str, prompt, CMD_BUFLEN);
+		strscpy(kdb_prompt_str, prompt, CMD_BUFLEN);
 	kdb_printf(kdb_prompt_str);
 	kdb_nextline = 1;	/* Prompt and input resets line number */
 	return kdb_read(buffer, bufsize);
-- 
1.9.1