linux-kernel - Re: [PATCH][drm-next] drm/amd/display: fix dereference of pointer fs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <f62f6823-228a-dff9-dad5-45b3fde9c5c2@amd.com>
Date:   Tue, 20 Nov 2018 20:08:00 +0000
From:   "Li, Sun peng (Leo)" <Sunpeng.Li@....com>
To:     Colin King <colin.king@...onical.com>,
        "Wentland, Harry" <Harry.Wentland@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhou, David(ChunMing)" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
CC:     "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][drm-next] drm/amd/display: fix dereference of pointer
 fs_params before it is null checked



On 2018-11-20 12:17 p.m., Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Currently there are several instances of pointer fs_params being
> dereferenced before fs_params is being null checked.  Fix this by
> only dereferencing fs_params after the null check.
> 
> Detected by CoverityScan, CID#1475565 ("Dereference before null check")
> 
> Fixes: e1e8a020c6b8 ("drm/amd/display: Add support for Freesync 2 HDR and Content to Display Mapping")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>

Reviewed-by: Leo Li <sunpeng.li@....com>

Thanks!

> ---
>   .../drm/amd/display/modules/color/color_gamma.c  | 16 +++++++++++-----
>   1 file changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
> index 7480f072c375..bbecbaefb741 100644
> --- a/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
> +++ b/drivers/gpu/drm/amd/display/modules/color/color_gamma.c
> @@ -813,20 +813,26 @@ static bool build_freesync_hdr(struct pwl_float_data_ex *rgb_regamma,
>   	const struct hw_x_point *coord_x = coordinate_x;
>   	struct fixed31_32 scaledX = dc_fixpt_zero;
>   	struct fixed31_32 scaledX1 = dc_fixpt_zero;
> -	struct fixed31_32 max_display = dc_fixpt_from_int(fs_params->max_display);
> -	struct fixed31_32 min_display = dc_fixpt_from_fraction(fs_params->min_display, 10000);
> -	struct fixed31_32 max_content = dc_fixpt_from_int(fs_params->max_content);
> -	struct fixed31_32 min_content = dc_fixpt_from_fraction(fs_params->min_content, 10000);
> +	struct fixed31_32 max_display;
> +	struct fixed31_32 min_display;
> +	struct fixed31_32 max_content;
> +	struct fixed31_32 min_content;
>   	struct fixed31_32 clip = dc_fixpt_one;
>   	struct fixed31_32 output;
>   	bool use_eetf = false;
>   	bool is_clipped = false;
> -	struct fixed31_32 sdr_white_level = dc_fixpt_from_int(fs_params->sdr_white_level);
> +	struct fixed31_32 sdr_white_level;
>   
>   	if (fs_params == NULL || fs_params->max_content == 0 ||
>   			fs_params->max_display == 0)
>   		return false;
>   
> +	max_display = dc_fixpt_from_int(fs_params->max_display);
> +	min_display = dc_fixpt_from_fraction(fs_params->min_display, 10000);
> +	max_content = dc_fixpt_from_int(fs_params->max_content);
> +	min_content = dc_fixpt_from_fraction(fs_params->min_content, 10000);
> +	sdr_white_level = dc_fixpt_from_int(fs_params->sdr_white_level);
> +
>   	if (fs_params->min_display > 1000) // cap at 0.1 at the bottom
>   		min_display = dc_fixpt_from_fraction(1, 10);
>   	if (fs_params->max_display < 100) // cap at 100 at the top
>