5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Fullway Wang <fullwaywang@xxxxxxxxxxx>
[ Upstream commit 04e5eac8f3ab2ff52fa191c187a46d4fdbc1e288 ]
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.
Although pixclock is checked in savagefb_decode_var(), but it is not
checked properly in savagefb_probe(). Fix this by checking whether
pixclock is zero in the function savagefb_check_var() before
info->var.pixclock is used as the divisor.
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>
---
drivers/video/fbdev/savage/savagefb_driver.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/savage/savagefb_driver.c b/drivers/video/fbdev/savage/savagefb_driver.c
index 0ac750cc5ea13..94ebd8af50cf7 100644
--- a/drivers/video/fbdev/savage/savagefb_driver.c
+++ b/drivers/video/fbdev/savage/savagefb_driver.c
@@ -868,6 +868,9 @@ static int savagefb_check_var(struct fb_var_screeninfo *var,
DBG("savagefb_check_var");
+ if (!var->pixclock)
+ return -EINVAL;
+
var->transp.offset = 0;
var->transp.length = 0;
switch (var->bits_per_pixel) {
--
2.43.0
