Subject: Re: [PATCH] gpu/drm/radeon:Fix null pointer risk
To:     Wen Zhiwei <wenzhiwei@kylinos.cn>, alexander.deucher@amd.com,
        Xinhui.Pan@amd.com, airlied@linux.ie, daniel@ffwll.ch
Cc:     amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <20211228073126.48906-1-wenzhiwei@kylinos.cn>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
Message-ID: <ec202938-5972-d74e-a17c-256420350eb8@amd.com>
Date:   Thu, 30 Dec 2021 17:36:58 +0100
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Am 28.12.21 um 08:31 schrieb Wen Zhiwei:
> If the null pointer is not judged in advance,
> there is a risk that the pointer will cross
> the boundary

As far as I can see that case is impossible, why do you want to add a 
check for it?

Regards,
Christian.

>
> Signed-off-by: Wen Zhiwei <wenzhiwei@kylinos.cn>
> ---
>   drivers/gpu/drm/radeon/radeon_vm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_vm.c b/drivers/gpu/drm/radeon/radeon_vm.c
> index bb53016f3138..d3d342041adf 100644
> --- a/drivers/gpu/drm/radeon/radeon_vm.c
> +++ b/drivers/gpu/drm/radeon/radeon_vm.c
> @@ -951,7 +951,7 @@ int radeon_vm_bo_update(struct radeon_device *rdev,
>   
>   		if (mem->mem_type == TTM_PL_TT) {
>   			bo_va->flags |= RADEON_VM_PAGE_SYSTEM;
> -			if (!(bo_va->bo->flags & (RADEON_GEM_GTT_WC | RADEON_GEM_GTT_UC)))
> +			if (bo_va->bo && !(bo_va->bo->flags & (RADEON_GEM_GTT_WC | RADEON_GEM_GTT_UC)))
>   				bo_va->flags |= RADEON_VM_PAGE_SNOOPED;
>   
>   		} else {