Hi,
On Jun 30 2016 23:56, Takashi Iwai wrote:
On Thu, 30 Jun 2016 16:04:44 +0200, Takashi Sakamoto wrote:
The 'dimen' field in struct snd_ctl_elem_info is used to compose all of members in the element as multi-dimensional matrix. The field has four members. Each member represents the width in each dimension level by element member unit. For example, if the members consist of typical two dimensional matrix, the dimen[0] represents the number of rows and dimen[1] represents the number of columns (or vise-versa).
The total members in the matrix should be within the number of members in the element, while current implementation has no validator of this information. In a view of userspace applications, the information must be valid so that it cannot cause any bugs such as buffer-over-run.
This commit adds a validator of dimension information for userspace applications which add new element sets. When they add the element sets with wrong dimension information, they receive -EINVAL.
Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp
sound/core/control.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)
diff --git a/sound/core/control.c b/sound/core/control.c index a85d455..af167ff 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -805,6 +805,33 @@ static int snd_ctl_elem_list(struct snd_card *card, return 0; }
+static bool validate_dimension(struct snd_ctl_elem_info *info) +{
- unsigned int elements;
- unsigned int i;
- /*
* When drivers don't use dimen field, this value is zero and pass the* validation. Else, calculated number of elements is validated.*/- elements = info->dimen.d[0];
- for (i = 1; i < ARRAY_SIZE(info->dimen.d); ++i) {
if (info->dimen.d[i] == 0)break;if (info->dimen.d[i] < 0)return false;elements *= info->dimen.d[i];- }
Just minor nit-picks:
No check for the negative sign of the first element?
It'd be clearer to check zero of the first element before the loop.
Safer to have an integer overflow check in such calculation.
Indeed. I'll post revised version, later.
Thanks
Takashi Sakamoto