[PATCH 5.13 12/22] drm/ttm: add a check against null pointer dereference

Greg Kroah-Hartman
2021-07-29T14:02:36Z

From: Zheyu Ma <zheyuma97@gmail.com>

[ Upstream commit 9e5c772954406829e928dbe59891d08938ead04b ]

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 <zheyuma97@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1626274459-8148-1-git-send-email-zheyuma97@gmail.com
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 707e5c152896..ed053fd15c90 100644
--- a/drivers/gpu/drm/ttm/ttm_range_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_range_manager.c
@@ -146,6 +146,9 @@ 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);
--
2.30.2