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References: <20210430082744.3638743-1-narmstrong@baylibre.com>
In-Reply-To: <20210430082744.3638743-1-narmstrong@baylibre.com>
From:   Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Date:   Mon, 3 May 2021 01:04:09 +0200
Message-ID: <CAFBinCC5piZDgyxezJp8Yi3Ny5B6WRD-XdWN7s2gm8_aqza=fg@mail.gmail.com>
Subject: Re: [PATCH] drm/meson: fix shutdown crash when component not probed
To:     Neil Armstrong <narmstrong@baylibre.com>
Cc:     dri-devel@lists.freedesktop.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Stefan Agner <stefan@agner.ch>
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On Fri, Apr 30, 2021 at 10:28 AM Neil Armstrong <narmstrong@baylibre.com> wrote:
>
> When main component is not probed, by example when the dw-hdmi module is
> not loaded yet or in probe defer, the following crash appears on shutdown:
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038
> ...
> pc : meson_drv_shutdown+0x24/0x50
> lr : platform_drv_shutdown+0x20/0x30
> ...
> Call trace:
> meson_drv_shutdown+0x24/0x50
> platform_drv_shutdown+0x20/0x30
> device_shutdown+0x158/0x360
> kernel_restart_prepare+0x38/0x48
> kernel_restart+0x18/0x68
> __do_sys_reboot+0x224/0x250
> __arm64_sys_reboot+0x24/0x30
> ...
>
> Simply check if the priv struct has been allocated before using it.
>
> Fixes: fa0c16caf3d7 ("drm: meson_drv add shutdown function")
> Reported-by: Stefan Agner <stefan@agner.ch>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>