linux-kernel - Re: [PATCH] drm/sun4i: Fix crash during suspend after component bind failure

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Date:   Thu, 16 Jun 2022 09:51:01 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Ondrej Jirman <megous@...ous.com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH] drm/sun4i: Fix crash during suspend after component bind
 failure

Hi,

On Wed, Jun 15, 2022 at 12:42:53AM -0500, Samuel Holland wrote:
> If the component driver fails to bind, or is unbound, the driver data
> for the top-level platform device points to a freed drm_device. If the
> system is then suspended, the driver passes this dangling pointer to
> drm_mode_config_helper_suspend(), which crashes.
> 
> Fix this by only setting the driver data while the platform driver holds
> a reference to the drm_device.
> 
> Fixes: 624b4b48d9d8 ("drm: sun4i: Add support for suspending the display driver")
> Signed-off-by: Samuel Holland <samuel@...lland.org>

Yeah, it's far from the only issue regarding structure lifetimes in the
driver.

We should convert as much as possible to the DRM-managed functions to
fix those.

Maxime

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