From: Zheyu Ma Date: Mon, 4 Apr 2022 08:47:21 +0000 (+0800) Subject: video: fbdev: tridentfb: Error out if 'pixclock' equals zero X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=16844e5870424c2728486dc0c0300ebf7fa09ad6;p=linux.git video: fbdev: tridentfb: Error out if 'pixclock' equals zero 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 error. Fix this by checking whether 'pixclock' is zero. The following log reveals it: divide error: 0000 [#1] PREEMPT SMP KASAN PTI RIP: 0010:tridentfb_check_var+0x853/0xe60 Call Trace: fb_set_var+0x367/0xeb0 do_fb_ioctl+0x234/0x670 fb_ioctl+0xdd/0x130 do_syscall_64+0x3b/0x90 Signed-off-by: Zheyu Ma Signed-off-by: Helge Deller --- diff --git a/drivers/video/fbdev/tridentfb.c b/drivers/video/fbdev/tridentfb.c index 4d20cb557ff0f..319131bd72cff 100644 --- a/drivers/video/fbdev/tridentfb.c +++ b/drivers/video/fbdev/tridentfb.c @@ -996,6 +996,9 @@ static int tridentfb_check_var(struct fb_var_screeninfo *var, int ramdac = 230000; /* 230MHz for most 3D chips */ debug("enter\n"); + if (!var->pixclock) + return -EINVAL; + /* check color depth */ if (bpp == 24) bpp = var->bits_per_pixel = 32;