This is a note to let you know that I've just added the patch titled
fbdev: tgafb: Fix potential divide by zero
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fbdev-tgafb-fix-potential-divide-by-zero.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 99fe0f01ff00c5a8b37568de84c03c0cf83be602
Author: Wei Chen <harperchen1110@xxxxxxxxx>
Date: Tue Mar 7 13:08:56 2023 +0000
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@xxxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/video/fbdev/tgafb.c b/drivers/video/fbdev/tgafb.c
index 65ba9921506e2..9d2912947eef6 100644
--- a/drivers/video/fbdev/tgafb.c
+++ b/drivers/video/fbdev/tgafb.c
@@ -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;
