Commit 521877bf authored Mar 07, 2023 by Wei Chen Committed by Greg Kroah-Hartman Apr 05, 2023

fbdev: tgafb: Fix potential divide by zero



[ Upstream commit f90bd245de82c095187d8c2cabb8b488a39eaecc ]

fb_set_var would by called when user invokes ioctl with cmd
FBIOPUT_VSCREENINFO. User-provided data would finally reach
tgafb_check_var. In case var->pixclock is assigned to zero,
divide by zero would occur when checking whether reciprocal
of var->pixclock is too high.

Similar crashes have happened in other fbdev drivers. There
is no check and modification on var->pixclock along the call
chain to tgafb_check_var. We believe it could also be triggered
in driver tgafb from user site.

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 7f12f99b

drivers/video/fbdev/tgafb.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -166,6 +166,9 @@ tgafb_check_var(struct fb_var_screeninfo var, struct fb_info info)
		{
		struct tga_par par = (struct tga_par )info->par;

		if (!var->pixclock)
		return -EINVAL;

		if (par->tga_type == TGA_TYPE_8PLANE) {
		if (var->bits_per_pixel != 8)
		return -EINVAL;