2022-07-25 10:59:39

by Alisa Khabibrakhmanova

Subject: [PATCH] drm/via: Add new condition to via_dma_cleanup()

Pointer dev_priv->mmio, which was checked for NULL at via_do_init_map(),
is passed to via_do_cleanup_map() and is dereferenced there without check.

The patch adds the condition in via_dma_cleanup() which prevents potential NULL
pointer dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 22f579c621e2 ("drm: Add via unichrome support")
Signed-off-by: Alisa Khabibrakhmanova <[email protected]>
---
drivers/gpu/drm/via/via_dma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/via/via_dma.c b/drivers/gpu/drm/via/via_dma.c
index 177b0499abf1..56bcbbf4ed54 100644
--- a/drivers/gpu/drm/via/via_dma.c
+++ b/drivers/gpu/drm/via/via_dma.c
@@ -164,7 +164,7 @@ int via_dma_cleanup(struct drm_device *dev)
drm_via_private_t *dev_priv =
(drm_via_private_t *) dev->dev_private;

- if (dev_priv->ring.virtual_start) {
+ if (dev_priv->ring.virtual_start && dev_priv->mmio) {
via_cmdbuf_reset(dev_priv);

drm_legacy_ioremapfree(&dev_priv->ring.map, dev);
--
2.34.1

2022-07-26 17:40:09

by Sam Ravnborg

Subject: Re: [PATCH] drm/via: Add new condition to via_dma_cleanup()

Hi Alisa,

On Mon, Jul 25, 2022 at 01:45:55PM +0300, Alisa Khabibrakhmanova wrote:
> Pointer dev_priv->mmio, which was checked for NULL at via_do_init_map(),
> is passed to via_do_cleanup_map() and is dereferenced there without check.
>
> The patch adds the condition in via_dma_cleanup() which prevents potential NULL
> pointer dereference.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 22f579c621e2 ("drm: Add via unichrome support")
> Signed-off-by: Alisa Khabibrakhmanova <[email protected]>

Thanks for your patch. Due to other changes in drm-misc where we
maintain the via driver this patch fails to apply.
It would be great if you could redo the patch after -rc2 - on top of
-next. Then we can apply it to drm-misc.

You will see that the individual files for the driver is merged to a
single file, and this change does not hit -next until later.

Sam

2022-07-29 09:26:14

by Alisa Khabibrakhmanova

Subject: [PATCH] drm/via: Add new condition to via_dma_cleanup()

Pointer dev_priv->mmio, which was checked for NULL at via_do_init_map(),
is passed to via_do_cleanup_map() and is dereferenced there without check.

The patch adds the condition in via_dma_cleanup() which prevents potential NULL
pointer dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 22f579c621e2 ("drm: Add via unichrome support")
Signed-off-by: Alisa Khabibrakhmanova <[email protected]>
---
drivers/gpu/drm/via/via_dri1.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/via/via_dri1.c b/drivers/gpu/drm/via/via_dri1.c
index d695d9291ece..691e3ceb0062 100644
--- a/drivers/gpu/drm/via/via_dri1.c
+++ b/drivers/gpu/drm/via/via_dri1.c
@@ -2961,7 +2961,7 @@ int via_dma_cleanup(struct drm_device *dev)
drm_via_private_t *dev_priv =
(drm_via_private_t *) dev->dev_private;

- if (dev_priv->ring.virtual_start) {
+ if (dev_priv->ring.virtual_start && dev_priv->mmio) {
via_cmdbuf_reset(dev_priv);

drm_legacy_ioremapfree(&dev_priv->ring.map, dev);
--
2.34.1

2022-09-06 19:35:32

by Daniel Vetter

Subject: Re: [PATCH] drm/via: Add new condition to via_dma_cleanup()

On Fri, Jul 29, 2022 at 12:06:43PM +0300, Alisa Khabibrakhmanova wrote:
> Pointer dev_priv->mmio, which was checked for NULL at via_do_init_map(),
> is passed to via_do_cleanup_map() and is dereferenced there without check.
>
> The patch adds the condition in via_dma_cleanup() which prevents potential NULL
> pointer dereference.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 22f579c621e2 ("drm: Add via unichrome support")
> Signed-off-by: Alisa Khabibrakhmanova <[email protected]>

This seems to have fallen through cracks, I applied it to drm-misc-next
now.

Thanks for your patch.
-Daniel

> ---
> drivers/gpu/drm/via/via_dri1.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/via/via_dri1.c b/drivers/gpu/drm/via/via_dri1.c
> index d695d9291ece..691e3ceb0062 100644
> --- a/drivers/gpu/drm/via/via_dri1.c
> +++ b/drivers/gpu/drm/via/via_dri1.c
> @@ -2961,7 +2961,7 @@ int via_dma_cleanup(struct drm_device *dev)
> drm_via_private_t *dev_priv =
> (drm_via_private_t *) dev->dev_private;
>
> - if (dev_priv->ring.virtual_start) {
> + if (dev_priv->ring.virtual_start && dev_priv->mmio) {
> via_cmdbuf_reset(dev_priv);
>
> drm_legacy_ioremapfree(&dev_priv->ring.map, dev);
> --
> 2.34.1
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch