4.19-stable review patch. If anyone has any objections, please let me know.
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From: Fullway Wang fullwaywang@outlook.com
[ 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@outlook.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/sis/sis_main.c | 2 ++ 1 file changed, 2 insertions(+)
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) {