On Sun, Jul 23, 2023 at 10:43 PM Guchun Chen <guchun.chen@xxxxxxx> wrote:
>
> Add a check to avoid null pointer dereference as below:
>
> [ 90.002283] general protection fault, probably for non-canonical
> address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
> [ 90.002292] KASAN: null-ptr-deref in range
> [0x0000000000000000-0x0000000000000007]
> [ 90.002346] ? exc_general_protection+0x159/0x240
> [ 90.002352] ? asm_exc_general_protection+0x26/0x30
> [ 90.002357] ? ttm_bo_evict_swapout_allowable+0x322/0x5e0 [ttm]
> [ 90.002365] ? ttm_bo_evict_swapout_allowable+0x42e/0x5e0 [ttm]
> [ 90.002373] ttm_bo_swapout+0x134/0x7f0 [ttm]
> [ 90.002383] ? __pfx_ttm_bo_swapout+0x10/0x10 [ttm]
> [ 90.002391] ? lock_acquire+0x44d/0x4f0
> [ 90.002398] ? ttm_device_swapout+0xa5/0x260 [ttm]
> [ 90.002412] ? lock_acquired+0x355/0xa00
> [ 90.002416] ? do_raw_spin_trylock+0xb6/0x190
> [ 90.002421] ? __pfx_lock_acquired+0x10/0x10
> [ 90.002426] ? ttm_global_swapout+0x25/0x210 [ttm]
> [ 90.002442] ttm_device_swapout+0x198/0x260 [ttm]
> [ 90.002456] ? __pfx_ttm_device_swapout+0x10/0x10 [ttm]
> [ 90.002472] ttm_global_swapout+0x75/0x210 [ttm]
> [ 90.002486] ttm_tt_populate+0x187/0x3f0 [ttm]
> [ 90.002501] ttm_bo_handle_move_mem+0x437/0x590 [ttm]
> [ 90.002517] ttm_bo_validate+0x275/0x430 [ttm]
> [ 90.002530] ? __pfx_ttm_bo_validate+0x10/0x10 [ttm]
> [ 90.002544] ? kasan_save_stack+0x33/0x60
> [ 90.002550] ? kasan_set_track+0x25/0x30
> [ 90.002554] ? __kasan_kmalloc+0x8f/0xa0
> [ 90.002558] ? amdgpu_gtt_mgr_new+0x81/0x420 [amdgpu]
> [ 90.003023] ? ttm_resource_alloc+0xf6/0x220 [ttm]
> [ 90.003038] amdgpu_bo_pin_restricted+0x2dd/0x8b0 [amdgpu]
> [ 90.003210] ? __x64_sys_ioctl+0x131/0x1a0
> [ 90.003210] ? do_syscall_64+0x60/0x90
>
> Fixes: a2848d08742c ("drm/ttm: never consider pinned BOs for eviction&swap")
> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@xxxxxxxxx>
> Signed-off-by: Guchun Chen <guchun.chen@xxxxxxx>
Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 7139a522b2f3..54e3083076b7 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -519,7 +519,8 @@ static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,
>
> if (bo->pin_count) {
> *locked = false;
> - *busy = false;
> + if (busy)
> + *busy = false;
> return false;
> }
>
> --
> 2.25.1
>
