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Date:   Tue, 20 Sep 2022 19:44:31 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Stefan Ghinea <stefan.ghinea@windriver.com>
Cc:     stable@vger.kernel.org, Zheyu Ma <zheyuma97@gmail.com>,
        Helge Deller <deller@gmx.de>
Subject: Re: [PATCH 5.10 1/1] video: fbdev: i740fb: Error out if 'pixclock'
 equals zero
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References: <20220919210302.29792-1-stefan.ghinea@windriver.com>
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On Tue, Sep 20, 2022 at 12:03:02AM +0300, Stefan Ghinea wrote:
> From: Zheyu Ma <zheyuma97@gmail.com>
> 
> commit 15cf0b82271b1823fb02ab8c377badba614d95d5 upstream
> 
> The userspace program could pass any values to the driver through
> ioctl() interface. If the driver doesn't check the value of 'pixclock',
> it may cause divide error.
> 
> Fix this by checking whether 'pixclock' is zero in the function
> i740fb_check_var().
> 
> The following log reveals it:
> 
> divide error: 0000 [#1] PREEMPT SMP KASAN PTI
> RIP: 0010:i740fb_decode_var drivers/video/fbdev/i740fb.c:444 [inline]
> RIP: 0010:i740fb_set_par+0x272f/0x3bb0 drivers/video/fbdev/i740fb.c:739
> Call Trace:
>     fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1036
>     do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1112
>     fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1191
>     vfs_ioctl fs/ioctl.c:51 [inline]
>     __do_sys_ioctl fs/ioctl.c:874 [inline]
> 
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
> Signed-off-by: Helge Deller <deller@gmx.de>
> Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com>
> ---
>  drivers/video/fbdev/i740fb.c | 3 +++
>  1 file changed, 3 insertions(+)

Both backports now queued up, thanks.

greg k-h