[PATCH 3.18 028/104] fbdev: fbmem: fix memory access if logo is bigger than the screen

Greg Kroah-Hartman
2019-04-24T17:11:59Z

[ Upstream commit a5399db139cb3ad9b8502d8b1bd02da9ce0b9df0 ]

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@ginzinger.com>
Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/video/fbdev/core/fbmem.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index ea2bd6208a2f..9eae191728d2 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -425,6 +425,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
{
unsigned int x;

+ if (image->width > info->var.xres || image->height > info->var.yres)
+ return;
+
if (rotate == FB_ROTATE_UR) {
for (x = 0;
x < num && image->dx + image->width <= info->var.xres;
--
2.19.1