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Subject: Re: [PATCH] drm/radeon: fix copy of uninitialized variable back to
 userspace
To:     Colin King <colin.king@canonical.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        =?UTF-8?B?TWFyZWsgT2zFocOhaw==?= <marek.olsak@amd.com>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Cc:     kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210303002759.28752-1-colin.king@canonical.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
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Date:   Wed, 3 Mar 2021 08:42:31 +0100
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Am 03.03.21 um 01:27 schrieb Colin King:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently the ioctl command RADEON_INFO_SI_BACKEND_ENABLED_MASK can
> copy back uninitialised data in value_tmp that pointer *value points
> to. This can occur when rdev->family is less than CHIP_BONAIRE and
> less than CHIP_TAHITI.  Fix this by adding in a missing -EINVAL
> so that no invalid value is copied back to userspace.
>
> Addresses-Coverity: ("Uninitialized scalar variable)
> Cc: stable@vger.kernel.org # 3.13+
> Fixes: 439a1cfffe2c ("drm/radeon: expose render backend mask to the userspace")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

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

Let's hope that this doesn't break UAPI.

Christian.

> ---
>   drivers/gpu/drm/radeon/radeon_kms.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
> index 2479d6ab7a36..58876bb4ef2a 100644
> --- a/drivers/gpu/drm/radeon/radeon_kms.c
> +++ b/drivers/gpu/drm/radeon/radeon_kms.c
> @@ -518,6 +518,7 @@ int radeon_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>   			*value = rdev->config.si.backend_enable_mask;
>   		} else {
>   			DRM_DEBUG_KMS("BACKEND_ENABLED_MASK is si+ only!\n");
> +			return -EINVAL;
>   		}
>   		break;
>   	case RADEON_INFO_MAX_SCLK: