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fbdev: tgafb: Fix potential divide by zero

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[ 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>
This commit is contained in:
Wei Chen 2023-03-07 13:08:56 +00:00 committed by Greg Kroah-Hartman
parent 7f12f99b80
commit 521877bf26
1 changed files with 3 additions and 0 deletions
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3
drivers/video/fbdev/tgafb.c
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@ -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; struct tga_par *par = (struct tga_par *)info->par;
if (!var->pixclock)
return -EINVAL;
if (par->tga_type == TGA_TYPE_8PLANE) { if (par->tga_type == TGA_TYPE_8PLANE) {
if (var->bits_per_pixel != 8) if (var->bits_per_pixel != 8)
return -EINVAL; return -EINVAL;