linux-kernel - Re: [PATCH 4/5] gma500: fix a missing break in cdv_intel_dp_set_m

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Message-ID: <CAMeQTsa1YeB2GFyUUJ2PJxACZ2dgWprN8mneka=VXDn5o-7+HA@mail.gmail.com>
Date:   Fri, 1 Apr 2022 12:03:10 +0200
From:   Patrik Jakobsson <patrik.r.jakobsson@...il.com>
To:     Xiaomeng Tong <xiam0nd.tong@...il.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Zhao Yakui <yakui.zhao@...el.com>,
        Dave Airlie <airlied@...hat.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5] gma500: fix a missing break in cdv_intel_dp_set_m_n

On Wed, Mar 30, 2022 at 2:03 PM Xiaomeng Tong <xiam0nd.tong@...il.com> wrote:
>
> Instead of exiting the loop as expected when an entry is found, the
> list_for_each_entry() continues until the traversal is complete. It
> could lead to a invalid reference to 'lane_count/bpp' after the loop.
>
> The invalid reference to 'lane_count/bpp' is here:
>         cdv_intel_dp_compute_m_n(bpp, lane_count,
>
> To fix this, when found the entry, add a break after the switch statement.
>
> Fixes: 8695b61294356 ("gma500: Add the support of display port on CDV")
> Signed-off-by: Xiaomeng Tong <xiam0nd.tong@...il.com>

This loop already breaks when the desired conditions are met (see the
if statements).

> ---
>  drivers/gpu/drm/gma500/cdv_intel_dp.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/gma500/cdv_intel_dp.c b/drivers/gpu/drm/gma500/cdv_intel_dp.c
> index ba6ad1466374..e6473b8da296 100644
> --- a/drivers/gpu/drm/gma500/cdv_intel_dp.c
> +++ b/drivers/gpu/drm/gma500/cdv_intel_dp.c
> @@ -1016,6 +1016,8 @@ cdv_intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
>                         bpp = dev_priv->edp.bpp;
>                         break;
>                 }
> +
> +               break;
>         }
>
>         /*
> --
> 2.17.1
>