2023-01-09 12:16:20

by Yang Yang

Subject: [PATCH linux-next] ALSA: control-led: use strscpy() to instead of strncpy()

From: Xu Panda <[email protected]>

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 <[email protected]>
Signed-off-by: Yang Yang <[email protected]>
---
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);
memset(&id, 0, sizeof(id));
id.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
s = buf2;
--
2.15.2

2023-01-09 13:02:51

by Takashi Iwai

Subject: Re: [PATCH linux-next] ALSA: control-led: use strscpy() to instead of strncpy()

On Mon, 09 Jan 2023 12:45:51 +0100,
<[email protected]> wrote:
>
> From: Xu Panda <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Yang Yang <[email protected]>
> ---
> 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()...?


thanks,

Takashi

2023-01-09 13:55:14

by Jaroslav Kysela

Subject: Re: [PATCH linux-next] ALSA: control-led: use strscpy() to instead of strncpy()

On 09. 01. 23 13:40, Takashi Iwai wrote:
> On Mon, 09 Jan 2023 12:45:51 +0100,
> <[email protected]> wrote:
>>
>> From: Xu Panda <[email protected]>
>>
>> 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 <[email protected]>
>> Signed-off-by: Yang Yang <[email protected]>
>> ---
>> 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 <[email protected]>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.