In function do_remove_conflicting_framebuffers, if device is NULL, there
will be null pointer reference. The patch add a check to the if expression.
Signed-off-by: Zhouyi Zhou <[email protected]>
---
Dear Linux folks
I discover this bug in the PowerPC VM provided by
Open source lab of Oregon State University:
https://lkml.org/lkml/2022/2/8/1145
I found that the root cause of null device field is in offb_init_fb:
info = framebuffer_alloc(sizeof(u32) * 16, NULL);
I have tested the patch in the PowerPC VM. Hope my patch can be correct.
Many Thanks
Zhouyi
--
drivers/video/fbdev/core/fbmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 34d6bb1bf82e..422b1fc01722 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1579,7 +1579,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
* If it's not a platform device, at least print a warning. A
* fix would add code to remove the device from the system.
*/
- if (dev_is_platform(device)) {
+ if (device && dev_is_platform(device)) {
registered_fb[i]->forced_out = true;
platform_device_unregister(to_platform_device(device));
} else {
--
2.25.1
On Thu, Feb 10, 2022 at 02:58:24PM +0800, Zhouyi Zhou wrote:
> In function do_remove_conflicting_framebuffers, if device is NULL, there
> will be null pointer reference. The patch add a check to the if expression.
>
> Signed-off-by: Zhouyi Zhou <[email protected]>
> ---
> Dear Linux folks
>
> I discover this bug in the PowerPC VM provided by
> Open source lab of Oregon State University:
>
> https://lkml.org/lkml/2022/2/8/1145
>
> I found that the root cause of null device field is in offb_init_fb:
> info = framebuffer_alloc(sizeof(u32) * 16, NULL);
>
> I have tested the patch in the PowerPC VM. Hope my patch can be correct.
This looks plausible to me, but I am quite unfamiliar with this code.
Thanx, Paul
> Many Thanks
> Zhouyi
> --
> drivers/video/fbdev/core/fbmem.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index 34d6bb1bf82e..422b1fc01722 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1579,7 +1579,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
> * If it's not a platform device, at least print a warning. A
> * fix would add code to remove the device from the system.
> */
> - if (dev_is_platform(device)) {
> + if (device && dev_is_platform(device)) {
> registered_fb[i]->forced_out = true;
> platform_device_unregister(to_platform_device(device));
> } else {
> --
> 2.25.1
>
Dear Zhouyi,
Am 10.02.22 um 07:58 schrieb Zhouyi Zhou:
> In function do_remove_conflicting_framebuffers, if device is NULL, there
> will be null pointer reference. The patch add a check to the if expression.
>
> Signed-off-by: Zhouyi Zhou <[email protected]>
> ---
> Dear Linux folks
>
> I discover this bug in the PowerPC VM provided by
> Open source lab of Oregon State University:
>
> https://lkml.org/lkml/2022/2/8/1145
>
> I found that the root cause of null device field is in offb_init_fb:
> info = framebuffer_alloc(sizeof(u32) * 16, NULL);
>
> I have tested the patch in the PowerPC VM. Hope my patch can be correct.
>
> Many Thanks
> Zhouyi
> --
> drivers/video/fbdev/core/fbmem.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index 34d6bb1bf82e..422b1fc01722 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1579,7 +1579,7 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
> * If it's not a platform device, at least print a warning. A
> * fix would add code to remove the device from the system.
> */
> - if (dev_is_platform(device)) {
> + if (device && dev_is_platform(device)) {
> registered_fb[i]->forced_out = true;
> platform_device_unregister(to_platform_device(device));
> } else {
Looks reasonable.
Acked-by: Paul Menzel <[email protected]>
Kind regards,
Paul
PS: Please note, this should be unrelated to my problem though, as I
didn’t use linux-next. (Let’s continue in the other thread though.)