Hi
Am 11.03.20 um 09:24 schrieb Takashi Iwai:
> On Wed, 11 Mar 2020 09:10:56 +0100,
> Thomas Zimmermann wrote:
>>
>> Hi Takashi
>>
>> Am 11.03.20 um 08:35 schrieb Takashi Iwai:
>>> Since snprintf() returns the would-be-output size instead of the
>>> actual output size, the succeeding calls may go beyond the given
>>> buffer limit. Fix it by replacing with scnprintf().
>>>
>>> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
>>> ---
>>> drivers/gpu/drm/drm_sysfs.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
>>> index dd2bc85f43cc..9b3180e8c12f 100644
>>> --- a/drivers/gpu/drm/drm_sysfs.c
>>> +++ b/drivers/gpu/drm/drm_sysfs.c
>>> @@ -230,7 +230,7 @@ static ssize_t modes_show(struct device *device,
>>>
>>> mutex_lock(&connector->dev->mode_config.mutex);
>>> list_for_each_entry(mode, &connector->modes, head) {
>>> - written += snprintf(buf + written, PAGE_SIZE - written, "%s\n",
>>> + written += scnprintf(buf + written, PAGE_SIZE - written, "%s\n",
>>> mode->name);
>>> }
>>> mutex_unlock(&connector->dev->mode_config.mutex);
>>>
>>
>> In drm_sysfs.c, there are more _show functions with calls to snprintf()
>> that could be replaced by scnprintf(). ATM they don't return the correct
>> length for output that exceeds PAGE_SIZE. since you're at it, you may
>> replace them as well.
>
> Well, the rest snprintf() calls are single calls and can't be over
> PAGE_SIZE obviously. IOW, they could be rather replaced with
> sprintf() instead, for a sake of simplicity.
Admittedly, none of these strings look as if they ever go beyond
PAGE_SIZE, but sncprintf() is still a simple way of defensive
programming here (and returns the correct value).
>
>> But in any case
>>
>> Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>>
>> for this patch.
>>
>> Do you want me to merge the patch into drm-misc-next?
>
> Yes, please.
OK, will do later today.
Best regards
Thomas
>
>
> thanks,
>
> Takashi
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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