From: Xu Panda <xu.panda@zte.com.cn>

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL terminated strings.

Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
---
 arch/x86/kernel/cpu/mce/dev-mcelog.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/dev-mcelog.c b/arch/x86/kernel/cpu/mce/dev-mcelog.c
index 100fbeebdc72..a05ac0716ecf 100644
--- a/arch/x86/kernel/cpu/mce/dev-mcelog.c
+++ b/arch/x86/kernel/cpu/mce/dev-mcelog.c
@@ -105,8 +105,7 @@ static ssize_t set_trigger(struct device *s, struct device_attribute *attr,
 {
 	char *p;

-	strncpy(mce_helper, buf, sizeof(mce_helper));
-	mce_helper[sizeof(mce_helper)-1] = 0;
+	strscpy(mce_helper, buf, sizeof(mce_helper));
 	p = strchr(mce_helper, '\n');

 	if (p)
-- 
2.15.2

On Sat, Dec 03, 2022 at 02:19:32PM +0800, yang.yang29@zte.com.cn wrote:
> From: Xu Panda <xu.panda@zte.com.cn>
> 
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL terminated strings.

It should read "NULL-terminated strings".

Thanks and BR,
Ricardo

>> The implementation of strscpy() is more robust and safer.
>> That's now the recommended way to copy NUL terminated strings.
>
> It should read "NULL-terminated strings".

Both "NUL-terminated" and "NULL-terminated" seem to be used in the kernel
source and commit comments.  NULL is ahead 124:45 in the source, but it
is closer in the commit logs where the ratio is 129:76.

Single "L" NUL seems technically more accurate as the string terminator is
an ascii NUL character. From man 5 ascii the character name is NUL (though
the description says "null" to muddy the waters)

       Oct   Dec   Hex   Char
       ───────────────────────────────────────────
       000   0     00    NUL '\0' (null character)

-Tony

On Wed, Dec 14, 2022 at 09:29:59PM +0000, Luck, Tony wrote:
> >> The implementation of strscpy() is more robust and safer.
> >> That's now the recommended way to copy NUL terminated strings.
> >
> > It should read "NULL-terminated strings".
> 
> Both "NUL-terminated" and "NULL-terminated" seem to be used in the kernel
> source and commit comments.  NULL is ahead 124:45 in the source, but it
> is closer in the commit logs where the ratio is 129:76.
> 
> Single "L" NUL seems technically more accurate as the string terminator is
> an ascii NUL character. From man 5 ascii the character name is NUL (though
> the description says "null" to muddy the waters)
> 
>        Oct   Dec   Hex   Char
>        ───────────────────────────────────────────
>        000   0     00    NUL '\0' (null character)

Thanks for the analysis Tony. Indeed, I agree that "NUL-terminated" is
more accurate.

Thanks and BR,
Ricardo

> From: Xu Panda <xu.panda@zte.com.cn>
>
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL terminated strings.

Reviewed-by: Tony Luck <tony.luck@intel.com>

The following commit has been merged into the x86/platform branch of tip:

Commit-ID:     7ddf0050a21fdcc025c3cb1055fe3db60df1cd97
Gitweb:        https://git.kernel.org/tip/7ddf0050a21fdcc025c3cb1055fe3db60df1cd97
Author:        Xu Panda <xu.panda@zte.com.cn>
AuthorDate:    Sat, 03 Dec 2022 14:19:32 +08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 07 Jan 2023 11:47:35 +01:00

x86/mce/dev-mcelog: use strscpy() to instead of strncpy()

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL terminated strings.

Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/202212031419324523731@zte.com.cn
---
 arch/x86/kernel/cpu/mce/dev-mcelog.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/dev-mcelog.c b/arch/x86/kernel/cpu/mce/dev-mcelog.c
index 100fbee..a05ac07 100644
--- a/arch/x86/kernel/cpu/mce/dev-mcelog.c
+++ b/arch/x86/kernel/cpu/mce/dev-mcelog.c
@@ -105,8 +105,7 @@ static ssize_t set_trigger(struct device *s, struct device_attribute *attr,
 {
 	char *p;
 
-	strncpy(mce_helper, buf, sizeof(mce_helper));
-	mce_helper[sizeof(mce_helper)-1] = 0;
+	strscpy(mce_helper, buf, sizeof(mce_helper));
 	p = strchr(mce_helper, '\n');
 
 	if (p)