Hi Dmitry,
I fear the following patch, and its 'Acked-by' from Nick Dyer, may
have gotten lost:
On Fri, Sep 16, 2011 at 3:40 AM, Daniel Kurtz <djkurtz@xxxxxxxxxxxx> wrote:
>
> Sysfs attribute show methods are always passed a buffer of length
> PAGE_SIZE. To keep from overwriting this buffer and causing havoc, use
> snprintf() to guarantee we never write more than the buffer can hold.
>
> In addition, at least for my touchscreen, the number and size of objects
> was far too big to fit in a single 4K page. Therefore, this patch also
> trims some redundant framing text to leave more room for actual data.
>
> Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
> ---
> drivers/input/touchscreen/atmel_mxt_ts.c | 21 +++++++++++++++------
> 1 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index f5d6685..a596c27 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -910,12 +910,17 @@ static ssize_t mxt_object_show(struct device *dev,
> for (i = 0; i < data->info.object_num; i++) {
> object = data->object_table + i;
>
> - count += sprintf(buf + count,
> - "Object Table Element %d(Type %d)\n",
> + count += snprintf(buf + count, PAGE_SIZE - count,
> + "Object[%d] (Type %d)\n",
> i + 1, object->type);
> + if (count >= PAGE_SIZE)
> + return PAGE_SIZE - 1;
>
> if (!mxt_object_readable(object->type)) {
> - count += sprintf(buf + count, "\n");
> + count += snprintf(buf + count, PAGE_SIZE - count,
> + "\n");
> + if (count >= PAGE_SIZE)
> + return PAGE_SIZE - 1;
> continue;
> }
>
> @@ -925,11 +930,15 @@ static ssize_t mxt_object_show(struct device *dev,
> if (error)
> return error;
>
> - count += sprintf(buf + count,
> - " Byte %d: 0x%x (%d)\n", j, val, val);
> + count += snprintf(buf + count, PAGE_SIZE - count,
> + "\t[%2d]: %02x (%d)\n", j, val, val);
> + if (count >= PAGE_SIZE)
> + return PAGE_SIZE - 1;
> }
>
> - count += sprintf(buf + count, "\n");
> + count += snprintf(buf + count, PAGE_SIZE - count, "\n");
> + if (count >= PAGE_SIZE)
> + return PAGE_SIZE - 1;
> }
>
> return count;
> --
> 1.7.3.1
>
On Thu, Oct 6, 2011 at 5:59 PM, Nick Dyer <nick.dyer@xxxxxxxxxxx> wrote:
> Hi Daniel-
>
> Just to introduce myself, I'm working for Atmel in UK on the atmel_mxt_ts
> driver.
>
> Daniel Kurtz wrote:
>> Sysfs attribute show methods are always passed a buffer of length
>> PAGE_SIZE. To keep from overwriting this buffer and causing havoc,
>> use snprintf() to guarantee we never write more than the buffer can
>> hold.
>>
>> In addition, at least for my touchscreen, the number and size of
>> objects was far too big to fit in a single 4K page. Therefore, this
>> patch also trims some redundant framing text to leave more room for
>> actual data.
>
> Yes, I'd noticed this problem as well. I was planning to address it by
> splitting up the file, but your patch looks like a good solution for now.
>
> I've tested it successfully on several chips.
>
> Acked-by: Nick Dyer <nick.dyer@xxxxxxxxxxx>
>
> --
> Nick Dyer
> Software Engineer, ITDev Ltd
>
> Hardware and Software Development Consultancy
>
> Email: nick.dyer@xxxxxxxxxxx
> Website: http://www.itdev.co.uk
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