Am 10.09.2018 um 14:05 schrieb Huang Rui:
On Mon, Sep 10, 2018 at 05:25:48PM +0800, Koenig, Christian wrote:
Am 10.09.2018 um 11:23 schrieb Huang Rui:
On Mon, Sep 10, 2018 at 11:00:04AM +0200, Christian König wrote:
Hi Ray,
well those patches doesn't make sense, the pointer is only local to the function.
You're right. I narrowed it with gdb dump from ttm_bo_bulk_move_lru_tail+0x2b, the use-after-free should be in below codes:
man = &bulk->tt[i].first->bdev->man[TTM_PL_TT]; ttm_bo_bulk_move_helper(&bulk->tt[i], &man->lru[i], false);
Is there a case, when orignal bo is destroyed in the bulk pos, but it doesn't update pos->first pointer, then we still use it during the bulk moving?
Only when a per VM BO is freed or the VM destroyed.
The first case should now be handled by "drm/amdgpu: set bulk_moveable to false when a per VM is released" and when we use a destroyed VM we would see other problems as well.
If a VM instance is teared down, all BOs which belong that VM should be removed from LRU. But how can we submit cmd based on a destroyed VM? You know, we do the bulk move at last step of submission.
Well exactly that's the point this can't happen :)
Otherwise we would crash because of using freed up memory much earlier in the command submission.
The best idea I have to track this down further is to add some trace_printk in ttm_bo_bulk_move_helper and amdgpu_bo_destroy and see why and when we are actually using a destroyed BO.
Christian.
Thanks, Ray
BTW: Just pushed this commit to the repository, should show up any second.
Christian.
Thanks, Ray
Regards, Christian.
Am 10.09.2018 um 10:57 schrieb Huang Rui:
It avoids to be refered again after freed.
Signed-off-by: Huang Rui ray.huang@amd.com Cc: Christian König christian.koenig@amd.com Cc: Tom StDenis Tom.StDenis@amd.com
drivers/gpu/drm/ttm/ttm_bo.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 138c989..d3ef5f8 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -54,6 +54,7 @@ static struct attribute ttm_bo_count = { static void ttm_bo_default_destroy(struct ttm_buffer_object *bo) { kfree(bo);
- bo = NULL; } static inline int ttm_mem_type_from_place(const struct ttm_place *place,
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