Nouveau - May 2018 - [PATCH][next] drm/nouveau/disp: avoid potential overflow on shift of int value

From: Colin Ian King <colin.king at canonical.com>

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 at canonical.com>
---
 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;
 	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

On Sun, May 27, 2018 at 5:54 PM, Colin King <colin.king at canonical.com>
wrote:
> From: Colin Ian King <colin.king at canonical.com>
>
> 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 at canonical.com>
> ---
>  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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