Re: [Nouveau] [PATCH][next] drm/nouveau/disp: avoid potential overflow on shift of int value

[Ilia Mirkin]

On Sun, May 27, 2018 at 5:54 PM, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> The constant values being shifted are 32 bit integers and may potentially
> overflow on the shift.  Avoid this potential overflow by making them
> unsigned long long values before the shift.
>
> Detected by CoverityScan, CID#1469383, 1469400 ("Unintentional
> integer overflow")
>
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/nouveau/nvkm/engine/disp/changf119.c | 2 +-
>  drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c  | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/changf119.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/changf119.c
> index 29e6dd58ac48..99b94802ed63 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/changf119.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/changf119.c
> @@ -52,7 +52,7 @@ void
>  gf119_disp_chan_intr(struct nv50_disp_chan *chan, bool en)
>  {
>         struct nvkm_device *device = chan->disp->base.engine.subdev.device;
> -       const u64 mask = 0x00000001 << chan->chid.user;
> +       const u64 mask = 0x00000001ULL << chan->chid.user;

I'm pretty sure all of these should just be u32 (below as well). The
registers that this is masking are all 32-bit, more doesn't make
sense.

>         if (!en) {
>                 nvkm_mask(device, 0x610090, mask, 0x00000000);
>                 nvkm_mask(device, 0x6100a0, mask, 0x00000000);
> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c
> index 57719f675eec..43ae3b092e43 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/channv50.c
> @@ -166,7 +166,7 @@ void
>  nv50_disp_chan_intr(struct nv50_disp_chan *chan, bool en)
>  {
>         struct nvkm_device *device = chan->disp->base.engine.subdev.device;
> -       const u64 mask = 0x00010001 << chan->chid.user;
> +       const u64 mask = 0x00010001ULL << chan->chid.user;
>         const u64 data = en ? 0x00010000 : 0x00000000;
>         nvkm_mask(device, 0x610028, mask, data);
>  }
> --
> 2.17.0
>
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