Messages in this thread | | | Date | Fri, 23 Jun 2023 09:51:29 +0200 | Subject | Re: [PATCH v3 03/11] media: videobuf2: Remove VB2_MAX_FRAME limit on buffer storage | From | Benjamin Gaignard <> |
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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 >>>
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