[PATCH] udmabuf: fix a buf size overflow issue during udmabuf creation

[Kasireddy, Vivek]

Hi Christian,

> Am 21.03.25 um 17:41 schrieb Xiaogang.Chen:
> > From: Xiaogang Chen <xiaogang.chen at amd.com>
> >
> > by casting size_limit_mb to u64  when calculate pglimit.
> >
> > Signed-off-by: Xiaogang Chen<Xiaogang.Chen at amd.com>
> 
> Reviewed-by: Christian König <christian.koenig at amd.com>
> 
> If nobody objects I'm going to push that to drm-misc-fixes.
No objection but I wish the author would have added more details in the commit
message particularly the value they have used to trigger the overflow. I guess
Xiaogang can still comment here and briefly describe the exact use-case/test-case
they are running where they encountered this issue.

Thanks,
Vivek

> 
> Regards,
> Christian.
> 
> > ---
> >  drivers/dma-buf/udmabuf.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> > index 8ce1f074c2d3..e99e3a65a470 100644
> > --- a/drivers/dma-buf/udmabuf.c
> > +++ b/drivers/dma-buf/udmabuf.c
> > @@ -398,7 +398,7 @@ static long udmabuf_create(struct miscdevice
> *device,
> >  	if (!ubuf)
> >  		return -ENOMEM;
> >
> > -	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
> > +	pglimit = ((u64)size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
> >  	for (i = 0; i < head->count; i++) {
> >  		pgoff_t subpgcnt;
> >