linux-kernel - Re: [PATCH] fbdev: fbmem: fix memory access if logo is bigger than the screen

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Date:   Fri, 8 Feb 2019 18:41:42 +0100
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     Martin Kepplinger <martink@...teo.de>
Cc:     linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        daniel.vetter@...ll.ch, manfred.schlaegl@...zinger.com,
        linux-kernel@...r.kernel.org,
        Martin Kepplinger <martin.kepplinger@...zinger.com>
Subject: Re: [PATCH] fbdev: fbmem: fix memory access if logo is bigger than
 the screen


On 01/28/2019 11:04 AM, Martin Kepplinger wrote:
> From: Manfred Schlaegl <manfred.schlaegl@...zinger.com>
> 
> There is no clipping on the x or y axis for logos larger that the framebuffer
> size. Therefore: a logo bigger than screen size leads to invalid memory access:
> 
> [    1.254664] Backtrace:
> [    1.254728] [<c02714e0>] (cfb_imageblit) from [<c026184c>] (fb_show_logo+0x620/0x684)
> [    1.254763]  r10:00000003 r9:00027fd8 r8:c6a40000 r7:c6a36e50 r6:00000000 r5:c06b81e4
> [    1.254774]  r4:c6a3e800
> [    1.254810] [<c026122c>] (fb_show_logo) from [<c026c1e4>] (fbcon_switch+0x3fc/0x46c)
> [    1.254842]  r10:c6a3e824 r9:c6a3e800 r8:00000000 r7:c6a0c000 r6:c070b014 r5:c6a3e800
> [    1.254852]  r4:c6808c00
> [    1.254889] [<c026bde8>] (fbcon_switch) from [<c029c8f8>] (redraw_screen+0xf0/0x1e8)
> [    1.254918]  r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:c070d5a0 r5:00000080
> [    1.254928]  r4:c6808c00
> [    1.254961] [<c029c808>] (redraw_screen) from [<c029d264>] (do_bind_con_driver+0x194/0x2e4)
> [    1.254991]  r9:00000000 r8:00000000 r7:00000014 r6:c070d5a0 r5:c070d5a0 r4:c070d5a0
> 
> So prevent displaying a logo bigger than screen size and avoid invalid
> memory access.
> 
> Signed-off-by: Manfred Schlaegl <manfred.schlaegl@...zinger.com>
> Signed-off-by: Martin Kepplinger <martin.kepplinger@...zinger.com>

Patch queued for v5.1, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics