Re: [PATCH v3 03/11] media: videobuf2: Remove VB2_MAX_FRAME limit on buffer storage

[Benjamin Gaignard]

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.

That will be in version 4.

Thanks,
Benjamin

> regards,
> dan carpenter