CVE-2022-49978: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: fbdev: fb_pm2fb: Avoid potential divide by zero error In `do_fb_ioctl()` of fbmem.c, if cmd is FBIOPUT_VSCREENINFO, var will be copied from user, then go through `fb_set_var()` and `info->fbops->fb_check_var()` which could may be `pm2fb_check_var()`. Along the path, `var->pixclock` won't be modified. This function checks whether reciprocal of `var->pixclock` is too high. If `var->pixclock` is zero, there will be a divide by zero error. So, it is necessary to check whether denominator is zero to avoid crash. As this bug is found by Syzkaller, logs are listed below. divide error in pm2fb_check_var Call Trace: <TASK> fb_set_var+0x367/0xeb0 drivers/video/fbdev/core/fbmem.c:1015 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189

Affected products

• Linux Linux Kernel: before 4.9.327 (fixed in 4.9.327); from 4.10, before 4.14.292 (fixed in 4.14.292); from 4.15, before 4.19.257 (fixed in 4.19.257); from 4.20, before 5.4.212 (fixed in 5.4.212); from 5.5, before 5.10.141 (fixed in 5.10.141); from 5.11, before 5.15.65 (fixed in 5.15.65); …

Published 2025-06-18. Last modified 2026-06-17.