From: Fullway Wang fullwaywang@outlook.com

stable inclusion from stable-v4.19.308 commit 84246c35ca34207114055a87552a1c4289c8fd7e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9E2MG CVE: CVE-2024-26777

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

[ 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 Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- 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 20aff9005978..b7f9da690db2 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) {