Hi Julian,
On Wed, Feb 17, 2016 at 5:38 AM, Julian Calaby <julian.calaby@xxxxxxxxx> wrote:
> Hi Souptick,
>
> On Tue, Feb 16, 2016 at 5:36 PM, Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote:
>> On Tue, Feb 16, 2016 at 12:34 AM, Alan <gnomes@xxxxxxxxxxxxxxxxxxx> wrote:
>>> The buffer needs to be zero terminated in case the user data is not.
>>> Otherwise we run off the end of the buffer.
>>>
>>> Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/net/wireless/ralink/rt2x00/rt2x00debug.c | 5 +++--
>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c b/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c
>>> index 25ee3cb..72ae530 100644
>>> --- a/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c
>>> +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c
>>> @@ -478,7 +478,7 @@ static ssize_t rt2x00debug_write_##__name(struct file *file, \
>>> { \
>>> struct rt2x00debug_intf *intf = file->private_data; \
>>> const struct rt2x00debug *debug = intf->debug; \
>>> - char line[16]; \
>>> + char line[17]; \
>>> size_t size; \
>>> unsigned int index = intf->offset_##__name; \
>>> __type value; \
>>> @@ -494,7 +494,8 @@ static ssize_t rt2x00debug_write_##__name(struct file *file, \
>>> \
>>> if (copy_from_user(line, buf, length)) \
>>> return -EFAULT; \
>>> - \
>>> + line[16] = 0;
>>
>> line[length] = '\0';
>> correct me if I am wrong. \
>
> I believe that in this case the data in buf will already be null
> terminated, so ensuring that line is null terminated is only needed if
> there are exactly 16 bytes in buf. IMHO
>
> line[16] = 0;
I think, if there are 16 bytes in buf, we end up loosing 1 byte data.
If there are 15 bytes in buf, buf is already be null terminated.
So is this really required?
Correct me if I am wrong.
>
> is dealing with this bug much more explicitly than
>
> line[length] = 0;
>
> however either will work. (BTW '\0' is identical to 0.)
>
> Thanks,
>
> --
> Julian Calaby
>
> Email: julian.calaby@xxxxxxxxx
> Profile: http://www.google.com/profiles/julian.calaby/
-Souptick
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