Re: [PATCH] kdb: Fix bound check compiler warning

From: Wenlin Kang
Date: Wed May 08 2019 - 22:57:53 EST

On 5/8/19 4:16 PM, Daniel Thompson wrote:
On Wed, May 08, 2019 at 09:52:39AM +0800, Wenlin Kang wrote:
The strncpy() function may leave the destination string buffer
unterminated, better use strlcpy() 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@xxxxxxxxxxxxx>
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..7fd4513 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);
+ strlcpy(kdb_prompt_str, prompt, CMD_BUFLEN);
Shouldn't that be strscpy?

Hi Daniel

I thought about strscpy, but I think strlcpy is better, because it only copy the real number of characters if src string less than that size.


kdb_nextline = 1; /* Prompt and input resets line number */
return kdb_read(buffer, bufsize);

Wenlin Kang