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SubjectRe: [PATCH linux-next] ALSA: control-led: use strscpy() to instead of strncpy()
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On 09. 01. 23 13:40, Takashi Iwai wrote:
> On Mon, 09 Jan 2023 12:45:51 +0100,
> <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.
>>
>> Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
>> Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
>> ---
>> sound/core/control_led.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/sound/core/control_led.c b/sound/core/control_led.c
>> index f975cc85772b..c88653c205eb 100644
>> --- a/sound/core/control_led.c
>> +++ b/sound/core/control_led.c
>> @@ -534,8 +534,7 @@ static ssize_t set_led_id(struct snd_ctl_led_card *led_card, const char *buf, si
>> struct snd_ctl_elem_id id;
>> int err;
>>
>> - strncpy(buf2, buf, len);
>> - buf2[len] = '\0';
>> + strncpy(buf2, buf, len + 1);
>
> Still using strncpy()...?

The original code should be:

diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index f975cc85772b..b44abefcb593 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -530,7 +530,7 @@ static ssize_t set_led_id(struct snd_ctl_led_card
*led_card, const char *buf, si
bool attach)
{
char buf2[256], *s, *os;
- size_t len = max(sizeof(s) - 1, count);
+ size_t len = min(sizeof(buf2) - 1, count);
struct snd_ctl_elem_id id;
int err;

But it can be replaced with:
diff --git a/sound/core/control_led.c b/sound/core/control_led.c
index f975cc85772b..41d4e898d34c 100644
--- a/sound/core/control_led.c
+++ b/sound/core/control_led.c
@@ -530,12 +530,11 @@ static ssize_t set_led_id(struct snd_ctl_led_card
*led_card, const char *buf, si
bool attach)
{
char buf2[256], *s, *os;
- size_t len = max(sizeof(s) - 1, count);
struct snd_ctl_elem_id id;
int err;

- strncpy(buf2, buf, len);
- buf2[len] = '\0';
+ if (strscpy(buf2, buf, count) < 0)
+ return -E2BIG;
memset(&id, 0, sizeof(id));
id.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
s = buf2;
I'll send a patch ASAP.

Jaroslav

--
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.

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