2021-07-14 14:55:45

by Zheyu Ma

Subject: [PATCH] drm/ttm: add a check against null pointer dereference

When calling ttm_range_man_fini(), 'man' may be uninitialized, which may
cause a null pointer dereference bug.

Fix this by checking if it is a null pointer.

This log reveals it:

[ 7.902580 ] BUG: kernel NULL pointer dereference, address: 0000000000000058
[ 7.905721 ] RIP: 0010:ttm_range_man_fini+0x40/0x160
[ 7.911826 ] Call Trace:
[ 7.911826 ] radeon_ttm_fini+0x167/0x210
[ 7.911826 ] radeon_bo_fini+0x15/0x40
[ 7.913767 ] rs400_fini+0x55/0x80
[ 7.914358 ] radeon_device_fini+0x3c/0x140
[ 7.914358 ] radeon_driver_unload_kms+0x5c/0xe0
[ 7.914358 ] radeon_driver_load_kms+0x13a/0x200
[ 7.914358 ] ? radeon_driver_unload_kms+0xe0/0xe0
[ 7.914358 ] drm_dev_register+0x1db/0x290
[ 7.914358 ] radeon_pci_probe+0x16a/0x230
[ 7.914358 ] local_pci_probe+0x4a/0xb0

Signed-off-by: Zheyu Ma <[email protected]>
---
drivers/gpu/drm/ttm/ttm_range_manager.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/ttm/ttm_range_manager.c b/drivers/gpu/drm/ttm/ttm_range_manager.c
index 03395386e8a7..f4b08a8705b3 100644
--- a/drivers/gpu/drm/ttm/ttm_range_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_range_manager.c
@@ -181,6 +181,9 @@ int ttm_range_man_fini(struct ttm_device *bdev,
struct drm_mm *mm = &rman->mm;
int ret;

+ if (!man)
+ return 0;
+
ttm_resource_manager_set_used(man, false);

ret = ttm_resource_manager_evict_all(bdev, man);
--
2.17.6

2021-07-14 15:07:31

by Christian König

Subject: Re: [PATCH] drm/ttm: add a check against null pointer dereference

Am 14.07.21 um 16:54 schrieb Zheyu Ma:
> When calling ttm_range_man_fini(), 'man' may be uninitialized, which may
> cause a null pointer dereference bug.
>
> Fix this by checking if it is a null pointer.

It would be better if the driver doesn't try to fini a manager which was
never initialized, but for now that should work.

>
> This log reveals it:
>
> [ 7.902580 ] BUG: kernel NULL pointer dereference, address: 0000000000000058
> [ 7.905721 ] RIP: 0010:ttm_range_man_fini+0x40/0x160
> [ 7.911826 ] Call Trace:
> [ 7.911826 ] radeon_ttm_fini+0x167/0x210
> [ 7.911826 ] radeon_bo_fini+0x15/0x40
> [ 7.913767 ] rs400_fini+0x55/0x80
> [ 7.914358 ] radeon_device_fini+0x3c/0x140
> [ 7.914358 ] radeon_driver_unload_kms+0x5c/0xe0
> [ 7.914358 ] radeon_driver_load_kms+0x13a/0x200
> [ 7.914358 ] ? radeon_driver_unload_kms+0xe0/0xe0
> [ 7.914358 ] drm_dev_register+0x1db/0x290
> [ 7.914358 ] radeon_pci_probe+0x16a/0x230
> [ 7.914358 ] local_pci_probe+0x4a/0xb0
>
> Signed-off-by: Zheyu Ma <[email protected]>

Reviewed-by: Christian König <[email protected]>

Going to push it later.

Thanks,
Christian.

> ---
> drivers/gpu/drm/ttm/ttm_range_manager.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_range_manager.c b/drivers/gpu/drm/ttm/ttm_range_manager.c
> index 03395386e8a7..f4b08a8705b3 100644
> --- a/drivers/gpu/drm/ttm/ttm_range_manager.c
> +++ b/drivers/gpu/drm/ttm/ttm_range_manager.c
> @@ -181,6 +181,9 @@ int ttm_range_man_fini(struct ttm_device *bdev,
> struct drm_mm *mm = &rman->mm;
> int ret;
>
> + if (!man)
> + return 0;
> +
> ttm_resource_manager_set_used(man, false);
>
> ret = ttm_resource_manager_evict_all(bdev, man);