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SubjectRe: [PATCH v3] drm/radeon: Fix NULL dereference when updating memory stats
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Am 24.06.21 um 06:51 schrieb Mikel Rychliski:
> radeon_ttm_bo_destroy() is attempting to access the resource object to
> update memory counters. However, the resource object is already freed when
> ttm calls this function via the destroy callback. This causes an oops when
> a bo is freed:
>
> BUG: kernel NULL pointer dereference, address: 0000000000000010
> RIP: 0010:radeon_ttm_bo_destroy+0x2c/0x100 [radeon]
> Call Trace:
> radeon_bo_unref+0x1a/0x30 [radeon]
> radeon_gem_object_free+0x33/0x50 [radeon]
> drm_gem_object_release_handle+0x69/0x70 [drm]
> drm_gem_handle_delete+0x62/0xa0 [drm]
> ? drm_mode_destroy_dumb+0x40/0x40 [drm]
> drm_ioctl_kernel+0xb2/0xf0 [drm]
> drm_ioctl+0x30a/0x3c0 [drm]
> ? drm_mode_destroy_dumb+0x40/0x40 [drm]
> radeon_drm_ioctl+0x49/0x80 [radeon]
> __x64_sys_ioctl+0x8e/0xd0
>
> Avoid the issue by updating the counters in the delete_mem_notify callback
> instead. Also, fix memory statistic updating in radeon_bo_move() to
> identify the source type correctly. The source type needs to be saved
> before the move, because the moved from object may be altered by the move.
>
> Fixes: bfa3357ef9ab ("drm/ttm: allocate resource object instead of embedding it v2")
> Signed-off-by: Mikel Rychliski <mikel@mikelr.com>

So, back from vacation. I've reviewed and pushed the patch to drm-misc-next.

Thanks for the help,
Christian.

> ---
> drivers/gpu/drm/radeon/radeon_object.c | 29 ++++++++++++-----------------
> drivers/gpu/drm/radeon/radeon_object.h | 2 +-
> drivers/gpu/drm/radeon/radeon_ttm.c | 13 ++++++++++---
> 3 files changed, 23 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
> index bfaaa3c969a3..56ede9d63b12 100644
> --- a/drivers/gpu/drm/radeon/radeon_object.c
> +++ b/drivers/gpu/drm/radeon/radeon_object.c
> @@ -49,23 +49,23 @@ static void radeon_bo_clear_surface_reg(struct radeon_bo *bo);
> * function are calling it.
> */
>
> -static void radeon_update_memory_usage(struct radeon_bo *bo,
> - unsigned mem_type, int sign)
> +static void radeon_update_memory_usage(struct ttm_buffer_object *bo,
> + unsigned int mem_type, int sign)
> {
> - struct radeon_device *rdev = bo->rdev;
> + struct radeon_device *rdev = radeon_get_rdev(bo->bdev);
>
> switch (mem_type) {
> case TTM_PL_TT:
> if (sign > 0)
> - atomic64_add(bo->tbo.base.size, &rdev->gtt_usage);
> + atomic64_add(bo->base.size, &rdev->gtt_usage);
> else
> - atomic64_sub(bo->tbo.base.size, &rdev->gtt_usage);
> + atomic64_sub(bo->base.size, &rdev->gtt_usage);
> break;
> case TTM_PL_VRAM:
> if (sign > 0)
> - atomic64_add(bo->tbo.base.size, &rdev->vram_usage);
> + atomic64_add(bo->base.size, &rdev->vram_usage);
> else
> - atomic64_sub(bo->tbo.base.size, &rdev->vram_usage);
> + atomic64_sub(bo->base.size, &rdev->vram_usage);
> break;
> }
> }
> @@ -76,8 +76,6 @@ static void radeon_ttm_bo_destroy(struct ttm_buffer_object *tbo)
>
> bo = container_of(tbo, struct radeon_bo, tbo);
>
> - radeon_update_memory_usage(bo, bo->tbo.resource->mem_type, -1);
> -
> mutex_lock(&bo->rdev->gem.mutex);
> list_del_init(&bo->list);
> mutex_unlock(&bo->rdev->gem.mutex);
> @@ -727,24 +725,21 @@ int radeon_bo_check_tiling(struct radeon_bo *bo, bool has_moved,
> }
>
> void radeon_bo_move_notify(struct ttm_buffer_object *bo,
> - bool evict,
> + unsigned int old_type,
> struct ttm_resource *new_mem)
> {
> struct radeon_bo *rbo;
>
> + radeon_update_memory_usage(bo, old_type, -1);
> + if (new_mem)
> + radeon_update_memory_usage(bo, new_mem->mem_type, 1);
> +
> if (!radeon_ttm_bo_is_radeon_bo(bo))
> return;
>
> rbo = container_of(bo, struct radeon_bo, tbo);
> radeon_bo_check_tiling(rbo, 0, 1);
> radeon_vm_bo_invalidate(rbo->rdev, rbo);
> -
> - /* update statistics */
> - if (!new_mem)
> - return;
> -
> - radeon_update_memory_usage(rbo, bo->resource->mem_type, -1);
> - radeon_update_memory_usage(rbo, new_mem->mem_type, 1);
> }
>
> vm_fault_t radeon_bo_fault_reserve_notify(struct ttm_buffer_object *bo)
> diff --git a/drivers/gpu/drm/radeon/radeon_object.h b/drivers/gpu/drm/radeon/radeon_object.h
> index 1739c6a142cd..1afc7992ef91 100644
> --- a/drivers/gpu/drm/radeon/radeon_object.h
> +++ b/drivers/gpu/drm/radeon/radeon_object.h
> @@ -161,7 +161,7 @@ extern void radeon_bo_get_tiling_flags(struct radeon_bo *bo,
> extern int radeon_bo_check_tiling(struct radeon_bo *bo, bool has_moved,
> bool force_drop);
> extern void radeon_bo_move_notify(struct ttm_buffer_object *bo,
> - bool evict,
> + unsigned int old_type,
> struct ttm_resource *new_mem);
> extern vm_fault_t radeon_bo_fault_reserve_notify(struct ttm_buffer_object *bo);
> extern int radeon_bo_get_surface_reg(struct radeon_bo *bo);
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
> index ad2a5a791bba..a06d4cc2fb1c 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -199,7 +199,7 @@ static int radeon_bo_move(struct ttm_buffer_object *bo, bool evict,
> struct ttm_resource *old_mem = bo->resource;
> struct radeon_device *rdev;
> struct radeon_bo *rbo;
> - int r;
> + int r, old_type;
>
> if (new_mem->mem_type == TTM_PL_TT) {
> r = radeon_ttm_tt_bind(bo->bdev, bo->ttm, new_mem);
> @@ -216,6 +216,9 @@ static int radeon_bo_move(struct ttm_buffer_object *bo, bool evict,
> if (WARN_ON_ONCE(rbo->tbo.pin_count > 0))
> return -EINVAL;
>
> + /* Save old type for statistics update */
> + old_type = old_mem->mem_type;
> +
> rdev = radeon_get_rdev(bo->bdev);
> if (old_mem->mem_type == TTM_PL_SYSTEM && bo->ttm == NULL) {
> ttm_bo_move_null(bo, new_mem);
> @@ -261,7 +264,7 @@ static int radeon_bo_move(struct ttm_buffer_object *bo, bool evict,
> out:
> /* update statistics */
> atomic64_add(bo->base.size, &rdev->num_bytes_moved);
> - radeon_bo_move_notify(bo, evict, new_mem);
> + radeon_bo_move_notify(bo, old_type, new_mem);
> return 0;
> }
>
> @@ -682,7 +685,11 @@ bool radeon_ttm_tt_is_readonly(struct radeon_device *rdev,
> static void
> radeon_bo_delete_mem_notify(struct ttm_buffer_object *bo)
> {
> - radeon_bo_move_notify(bo, false, NULL);
> + unsigned int old_type = TTM_PL_SYSTEM;
> +
> + if (bo->resource)
> + old_type = bo->resource->mem_type;
> + radeon_bo_move_notify(bo, old_type, NULL);
> }
>
> static struct ttm_device_funcs radeon_bo_driver = {

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