Re: [PATCH] drm/amdgpu: return -EFAULT if copy_to_user() fails

From: "Christian König" <christian.koenig@amd.com>
To: Dan Carpenter <dan.carpenter@oracle.com>,
	Alex Deucher <alexander.deucher@amd.com>
Cc: "David \(ChunMing\) Zhou" <David1.Zhou@amd.com>,
	Jonathan Kim <Jonathan.Kim@amd.com>,
	Philip Yang <Philip.Yang@amd.com>,
	David Airlie <airlied@linux.ie>,
	Felix Kuehling <Felix.Kuehling@amd.com>,
	"Tianci.Yin" <tianci.yin@amd.com>,
	kernel-janitors@vger.kernel.org, amd-gfx@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org, Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH] drm/amdgpu: return -EFAULT if copy_to_user() fails
Date: Wed, 12 Feb 2020 13:12:17 +0100	[thread overview]
Message-ID: <577d76db-3c2d-545d-6237-1c66f17ec178@amd.com> (raw)
In-Reply-To: <20200212120759.dokjxbk4cqln55sc@kili.mountain>

Am 12.02.20 um 13:07 schrieb Dan Carpenter:
> The copy_to_user() function returns the number of bytes remaining to be
> copied, but we want to return a negative error code to the user.
>
> Fixes: 030d5b97a54b ("drm/amdgpu: use amdgpu_device_vram_access in amdgpu_ttm_vram_read")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

Alex do you want to pick that up or should I do this?

Thanks,
Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 15f5451d312d..660867cf2597 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -2280,7 +2280,6 @@ static ssize_t amdgpu_ttm_vram_read(struct file *f, char __user *buf,
>   {
>   	struct amdgpu_device *adev = file_inode(f)->i_private;
>   	ssize_t result = 0;
> -	int r;
>   
>   	if (size & 0x3 || *pos & 0x3)
>   		return -EINVAL;
> @@ -2294,9 +2293,8 @@ static ssize_t amdgpu_ttm_vram_read(struct file *f, char __user *buf,
>   		uint32_t value[AMDGPU_TTM_VRAM_MAX_DW_READ];
>   
>   		amdgpu_device_vram_access(adev, *pos, value, bytes, false);
> -		r = copy_to_user(buf, value, bytes);
> -		if (r)
> -			return r;
> +		if (copy_to_user(buf, value, bytes))
> +			return -EFAULT;
>   
>   		result += bytes;
>   		buf += bytes;

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