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 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@outlook.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c09d7426cd925..d9eafdb89ceaf 100644 --- a/drivers/video/fbdev/savage/savagefb_driver.c +++ b/drivers/video/fbdev/savage/savagefb_driver.c @@ -869,6 +869,9 @@ 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) {