From: Zheyu Ma Date: Thu, 4 Aug 2022 12:41:24 +0000 (+0800) Subject: video: fbdev: arkfb: Check the size of screen before memset_io() X-Git-Tag: baikal/mips/sdk5.9~114 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=c831a334220cd25dbf0b388c33f81d6689d74626;p=kernel.git video: fbdev: arkfb: Check the size of screen before memset_io() [ Upstream commit e04d54793e947de1cb45c7aba412f68bed9a6f89 ] 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: dbd58d3aadcf ("arkfb: new framebuffer driver for ARK Logic cards") Signed-off-by: Zheyu Ma Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c index d94cc5ad1ef67..8d092b1064706 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);