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Date:   Thu, 3 Mar 2022 11:16:27 +0100
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Subject: Re: [PATCH] video: fbdev: sm712fb: Fix crash in smtcfb_write()
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To:     Zheyu Ma <zheyuma97@gmail.com>
Cc:     sudipm.mukherjee@gmail.com, teddy.wang@siliconmotion.com,
        linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <20220302143311.2109322-1-zheyuma97@gmail.com>
 <666d1565-0467-bb21-916b-073392129e1a@gmx.de>
 <CAMhUBj=P82_f6LdhWqEbe06SRPrMU2jxquNzgWkrttGDy6C4Kg@mail.gmail.com>
From:   Helge Deller <deller@gmx.de>
In-Reply-To: <CAMhUBj=P82_f6LdhWqEbe06SRPrMU2jxquNzgWkrttGDy6C4Kg@mail.gmail.com>
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On 3/3/22 02:34, Zheyu Ma wrote:
> Hi,
>
> On Thu, Mar 3, 2022 at 12:49 AM Helge Deller <deller@gmx.de> wrote:
>>
>> On 3/2/22 15:33, Zheyu Ma wrote:
>>> When the sm712fb driver writes three bytes to the framebuffer, the
>>> driver will crash:
>>>
>>>     BUG: unable to handle page fault for address: ffffc90001ffffff
>>>     RIP: 0010:smtcfb_write+0x454/0x5b0
>>>     Call Trace:
>>>      vfs_write+0x291/0xd60
>>>      ? do_sys_openat2+0x27d/0x350
>>>      ? __fget_light+0x54/0x340
>>>      ksys_write+0xce/0x190
>>>      do_syscall_64+0x43/0x90
>>>      entry_SYSCALL_64_after_hwframe+0x44/0xae
>>>
>>> Fix it by removing the open-coded endianness fixup-code.
>>>
>>> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
>>
>> Thanks... it's already in the fbdev git tree and queued up for v5.18...
>> https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/=
commit/?h=3Dfor-next&id=3Dbd771cf5c4254511cc4abb88f3dab3bd58bdf8e8
>
> This patch fixes the crash in smtcfb_read(), but there is a similar
> bug in smtcfb_write(), and I mocked up your patch a wrote a new patch
> for it.
> So we should fix two bugs with two patches.

Right, I missed the read() code.

I applied your patch now to the fbdev for-next git tree.

Thanks!
Helge


>
> Regards,
> Zheyu Ma