[PATCH v3 03/11] media: videobuf2: Remove VB2_MAX_FRAME limit on buffer storage
Benjamin Gaignard
benjamin.gaignard at collabora.com
Fri Jun 23 00:51:29 PDT 2023
Le 23/06/2023 à 09:02, Hans Verkuil a écrit :
> On 22/06/2023 16:13, Benjamin Gaignard wrote:
>> Le 22/06/2023 à 16:11, Dan Carpenter a écrit :
>>> On Thu, Jun 22, 2023 at 03:13:41PM +0200, Benjamin Gaignard wrote:
>>>> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
>>>> index f1ff7af34a9f..86e1e926fa45 100644
>>>> --- a/drivers/media/common/videobuf2/videobuf2-core.c
>>>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
>>>> @@ -455,9 +455,9 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
>>>> struct vb2_buffer *vb;
>>>> int ret;
>>>> - /* Ensure that q->num_buffers+num_buffers is below VB2_MAX_FRAME */
>>>> + /* Ensure that q->num_buffers + num_buffers is UINT_MAX */
>>>> num_buffers = min_t(unsigned int, num_buffers,
>>>> - VB2_MAX_FRAME - q->num_buffers);
>>>> + UINT_MAX - q->num_buffers);
>>>> for (buffer = 0; buffer < num_buffers; ++buffer) {
>>>> /* Allocate vb2 buffer structures */
>>> Ah... Here's one of the integer overflow bugs I was talking about. The
>>> __vb2_queue_alloc() function returns an int so if num_buffers goes over
>>> INT_MAX we are hosed.
>> I will limit it to:
>> #define VB2_QUEUE_MAX_BUFFERS (INT_MAX & PAGE_MASK) /* The mask prevents 85% of integer overflows */
>> as you have suggest it.
> IMHO INT_MAX is way overkill. How about (1U << 20)? I would like some sort of
> sanity check here. 1048576 buffers of 640x480 and 4 bytes per pixel is 1.2 TB.
I will go for (1U << 20) in next version.
Regards,
Benjamin
>
> Since a TB of memory is doable these days, I think this is a reasonable
> value for MAX_BUFFERS without allowing just anything.
>
> An alternative is to make this a kernel config.
>
> Regards,
>
> Hans
>
>> That will be in version 4.
>>
>> Thanks,
>> Benjamin
>>
>>> regards,
>>> dan carpenter
>>>
More information about the Linux-rockchip
mailing list