[PATCH] drm/vmwgfx: Fix invalid reads in fence signaled events

[PATCH] drm/vmwgfx: Fix invalid reads in fence signaled events

[Zack Rusin]

Correctly set the length of the drm_event to the size of the structure
that's actually used.

The length of the drm_event was set to the parent structure instead of
to the drm_vmw_event_fence which is supposed to be read. drm_read
uses the length parameter to copy the event to the user space thus
resuling in oob reads.

Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Fixes: 8b7de6aa8468 ("vmwgfx: Rework fence event action")
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-23566
Cc: David Airlie <airlied@gmail.com>
CC: Daniel Vetter <daniel@ffwll.ch>
Cc: Zack Rusin <zack.rusin@broadcom.com>
Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Cc: <stable@vger.kernel.org> # v3.4+
---
 drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index 2a0cda324703..5efc6a766f64 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -991,7 +991,7 @@ static int vmw_event_fence_action_create(struct drm_file *file_priv,
 	}
 
 	event->event.base.type = DRM_VMW_EVENT_FENCE_SIGNALED;
-	event->event.base.length = sizeof(*event);
+	event->event.base.length = sizeof(event->event);
 	event->event.user_data = user_data;
 
 	ret = drm_event_reserve_init(dev, file_priv, &event->base, &event->event.base);
-- 
2.40.1

Re: [PATCH] drm/vmwgfx: Fix invalid reads in fence signaled events

[Maaz Mombasawala]

On 4/25/24 12:27, Zack Rusin wrote:
> Correctly set the length of the drm_event to the size of the structure
> that's actually used.
> 
> The length of the drm_event was set to the parent structure instead of
> to the drm_vmw_event_fence which is supposed to be read. drm_read
> uses the length parameter to copy the event to the user space thus
> resuling in oob reads.
> 
> Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
> Fixes: 8b7de6aa8468 ("vmwgfx: Rework fence event action")
> Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-23566
> Cc: David Airlie <airlied@gmail.com>
> CC: Daniel Vetter <daniel@ffwll.ch>
> Cc: Zack Rusin <zack.rusin@broadcom.com>
> Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Cc: <stable@vger.kernel.org> # v3.4+
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
> index 2a0cda324703..5efc6a766f64 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
> @@ -991,7 +991,7 @@ static int vmw_event_fence_action_create(struct drm_file *file_priv,
>  	}
>  
>  	event->event.base.type = DRM_VMW_EVENT_FENCE_SIGNALED;
> -	event->event.base.length = sizeof(*event);
> +	event->event.base.length = sizeof(event->event);
>  	event->event.user_data = user_data;
>  
>  	ret = drm_event_reserve_init(dev, file_priv, &event->base, &event->event.base);

LGTM!

Reviewed-by: Maaz Mombasawala <maaz.mombasawala@broadcom.com>

Thanks,

Maaz Mombasawala <maaz.mombasawala@broadcom.com>

Re: [PATCH] drm/vmwgfx: Fix invalid reads in fence signaled events

[Martin Krastev]

LGTM!

Reviewed-by: Martin Krastev <martin.krastev@broadcom.com>

Regards,
Martin

On Thu, Apr 25, 2024 at 10:27 PM Zack Rusin <zack.rusin@broadcom.com> wrote:
>
> Correctly set the length of the drm_event to the size of the structure
> that's actually used.
>
> The length of the drm_event was set to the parent structure instead of
> to the drm_vmw_event_fence which is supposed to be read. drm_read
> uses the length parameter to copy the event to the user space thus
> resuling in oob reads.
>
> Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
> Fixes: 8b7de6aa8468 ("vmwgfx: Rework fence event action")
> Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-23566
> Cc: David Airlie <airlied@gmail.com>
> CC: Daniel Vetter <daniel@ffwll.ch>
> Cc: Zack Rusin <zack.rusin@broadcom.com>
> Cc: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Cc: <stable@vger.kernel.org> # v3.4+
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_fence.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
> index 2a0cda324703..5efc6a766f64 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
> @@ -991,7 +991,7 @@ static int vmw_event_fence_action_create(struct drm_file *file_priv,
>         }
>
>         event->event.base.type = DRM_VMW_EVENT_FENCE_SIGNALED;
> -       event->event.base.length = sizeof(*event);
> +       event->event.base.length = sizeof(event->event);
>         event->event.user_data = user_data;
>
>         ret = drm_event_reserve_init(dev, file_priv, &event->base, &event->event.base);
> --
> 2.40.1
>