From: Zheyu Ma zheyuma97@gmail.com
[ Upstream commit 96b550971c65d54d64728d8ba973487878a06454 ]
In the function arkfb_set_par(), the value of 'screen_size' is calculated by the user input. If the user provides the improper value, the value of 'screen_size' may larger than 'info->screen_size', which may cause the following bug:
[ 659.399066] BUG: unable to handle page fault for address: ffffc90003000000 [ 659.399077] #PF: supervisor write access in kernel mode [ 659.399079] #PF: error_code(0x0002) - not-present page [ 659.399094] RIP: 0010:memset_orig+0x33/0xb0 [ 659.399116] Call Trace: [ 659.399122] arkfb_set_par+0x143f/0x24c0 [ 659.399130] fb_set_var+0x604/0xeb0 [ 659.399161] do_fb_ioctl+0x234/0x670 [ 659.399189] fb_ioctl+0xdd/0x130
Fix the this by checking the value of 'screen_size' before memset_io().
Fixes: 681e14730c73 ("arkfb: new framebuffer driver for ARK Logic cards") Signed-off-by: Zheyu Ma zheyuma97@gmail.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/arkfb.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c index d94cc5ad1ef6..8d092b106470 100644 --- a/drivers/video/fbdev/arkfb.c +++ b/drivers/video/fbdev/arkfb.c @@ -794,6 +794,8 @@ static int arkfb_set_par(struct fb_info *info) value = ((value * hmul / hdiv) / 8) - 5; vga_wcrt(par->state.vgabase, 0x42, (value + 1) / 2);
+ if (screen_size > info->screen_size) + screen_size = info->screen_size; memset_io(info->screen_base, 0x00, screen_size); /* Device and screen back on */ svga_wcrt_mask(par->state.vgabase, 0x17, 0x80, 0x80);