CVE-2022-50102

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

video: fbdev: arkfb: Fix a divide-by-zero bug in ark_set_pixclock()

Since the user can control the arguments of the ioctl() from the user

space, under special arguments that may result in a divide-by-zero bug

in:

drivers/video/fbdev/arkfb.c:784: ark_set_pixclock(info, (hdiv * info->var.pixclock) / hmul);

with hdiv=1, pixclock=1 and hmul=2 you end up with (1*1)/2 = (int) 0.

and then in:

drivers/video/fbdev/arkfb.c:504: rv = dac_set_freq(par->dac, 0, 1000000000 / pixclock);

we'll get a division-by-zero.

The following log can reveal it:

divide error: 0000 [#1] PREEMPT SMP KASAN PTI

RIP: 0010:ark_set_pixclock drivers/video/fbdev/arkfb.c:504 [inline]

RIP: 0010:arkfb_set_par+0x10fc/0x24c0 drivers/video/fbdev/arkfb.c:784

Call Trace:

fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1034

do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110

fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189

Fix

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References