This is a note to let you know that I've just added the patch titled
fbdev: sis: Error out if pixclock equals 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-sis-error-out-if-pixclock-equals-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 3d576383a5d1ab74eaa5984b774fbf341d462b8e
Author: Fullway Wang <fullwaywang@xxxxxxxxxxx>
Date: Thu Jan 18 14:24:43 2024 +0800
fbdev: sis: Error out if pixclock equals zero
[ Upstream commit e421946be7d9bf545147bea8419ef8239cb7ca52 ]
The userspace program could pass any values to the driver through
ioctl() interface. If the driver doesn't check the value of pixclock,
it may cause divide-by-zero error.
In sisfb_check_var(), var->pixclock is used as a divisor to caculate
drate before it is checked against zero. Fix this by checking it
at the beginning.
This is similar to CVE-2022-3061 in i740fb which was fixed by
commit 15cf0b8.
Signed-off-by: Fullway Wang <fullwaywang@xxxxxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/video/fbdev/sis/sis_main.c b/drivers/video/fbdev/sis/sis_main.c
index 20aff90059781..b7f9da690db27 100644
--- a/drivers/video/fbdev/sis/sis_main.c
+++ b/drivers/video/fbdev/sis/sis_main.c
@@ -1488,6 +1488,8 @@ sisfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
vtotal = var->upper_margin + var->lower_margin + var->vsync_len;
+ if (!var->pixclock)
+ return -EINVAL;
pixclock = var->pixclock;
if((var->vmode & FB_VMODE_MASK) == FB_VMODE_NONINTERLACED) {
