2021-12-01 05:22:31

by Ricardo Ribalda

Subject: [PATCH v2 1/2] media: uvcvideo: Avoid invalid memory access

If mappings points to an invalid memory, we will be invalid accessing
it.
Solve it by initializing the value of the variable mapping and by
changing the order in the conditional statement (to avoid accessing
mapping->id if not needed).

Fix:
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN NOPTI

Fixes: 6350d6a4ed487 ("media: uvcvideo: Set error_idx during ctrl_commit errors")
Signed-off-by: Ricardo Ribalda <[email protected]>
---
drivers/media/usb/uvc/uvc_ctrl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 30bfe9069a1f..9a25d6029255 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1638,7 +1638,7 @@ static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
struct v4l2_ext_controls *ctrls,
struct uvc_control *uvc_control)
{
- struct uvc_control_mapping *mapping;
+ struct uvc_control_mapping *mapping = NULL;
struct uvc_control *ctrl_found;
unsigned int i;

--
2.34.0.rc2.393.gf8c9666880-goog

2021-12-01 05:22:32

by Ricardo Ribalda

Subject: [PATCH v2 2/2] media: uvcvideo: Avoid returning invalid controls

If the memory where ctrl_found is placed has the value of uvc_ctrl and
__uvc_find_control does not find the control we will return an invalid
index.

Fixes: 6350d6a4ed487 ("media: uvcvideo: Set error_idx during ctrl_commit errors")
Reviewed-by: Laurent Pinchart <[email protected]>
Signed-off-by: Ricardo Ribalda <[email protected]>
---
drivers/media/usb/uvc/uvc_ctrl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 9a25d6029255..b4f6edf968bc 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1639,7 +1639,7 @@ static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
struct uvc_control *uvc_control)
{
struct uvc_control_mapping *mapping = NULL;
- struct uvc_control *ctrl_found;
+ struct uvc_control *ctrl_found = NULL;
unsigned int i;

if (!entity)
--
2.34.0.rc2.393.gf8c9666880-goog

2021-12-01 05:43:00

by Laurent Pinchart

Subject: Re: [PATCH v2 1/2] media: uvcvideo: Avoid invalid memory access

Hi Ricardo,

Thank you for the patch.

On Wed, Dec 01, 2021 at 06:22:17AM +0100, Ricardo Ribalda wrote:
> If mappings points to an invalid memory, we will be invalid accessing
> it.

I'll reflow the commit message.

> Solve it by initializing the value of the variable mapping and by
> changing the order in the conditional statement (to avoid accessing
> mapping->id if not needed).
>
> Fix:
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] PREEMPT SMP KASAN NOPTI
>
> Fixes: 6350d6a4ed487 ("media: uvcvideo: Set error_idx during ctrl_commit errors")
> Signed-off-by: Ricardo Ribalda <[email protected]>

Reviewed-by: Laurent Pinchart <[email protected]>

> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index 30bfe9069a1f..9a25d6029255 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1638,7 +1638,7 @@ static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
> struct v4l2_ext_controls *ctrls,
> struct uvc_control *uvc_control)
> {
> - struct uvc_control_mapping *mapping;
> + struct uvc_control_mapping *mapping = NULL;
> struct uvc_control *ctrl_found;
> unsigned int i;
>

--
Regards,

Laurent Pinchart