CVE-2021-47641

low-risk

Published 2025-02-26

In the Linux kernel, the following vulnerability has been resolved: video: fbdev: cirrusfb: check pixclock to avoid divide by zero Do a sanity check on pixclock value to avoid divide by zero. If the pixclock value is zero, the cirrusfb driver will round up pixclock to get the derived frequency as close to maxclock as possible. Syzkaller reported a divide error in cirrusfb_check_pixclock. divide error: 0000 [#1] SMP KASAN PTI CPU: 0 PID: 14938 Comm: cirrusfb_test Not tainted 5.15.0-rc6 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2 RIP: 0010:cirrusfb_check_var+0x6f1/0x1260 Call Trace: fb_set_var+0x398/0xf90 do_fb_ioctl+0x4b8/0x6f0 fb_ioctl+0xeb/0x130 __x64_sys_ioctl+0x19d/0x220 do_syscall_64+0x3a/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae

Do I need to act?

0.02% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 5.5/10 Medium

LOCAL / LOW complexity

Affected Products (1)

Linux Kernel

Affected Vendors

Linux

References (9)

Patch https://git.kernel.org/stable/c/1d3fb46439ad4e8f0c5739eb33d1875ac9e0f135

Patch https://git.kernel.org/stable/c/40b13e3d85744210db13457785646634e2d056bd

Patch https://git.kernel.org/stable/c/45800c42ef000f417270bcfc08630e42486fca99

Patch https://git.kernel.org/stable/c/53a2088a396cfa1da92690a1da289634cd73bf0d

Patch https://git.kernel.org/stable/c/5c6f402bdcf9e7239c6bc7087eda71ac99b31379

Patch https://git.kernel.org/stable/c/6fe23ff94e7840097202e85c148688940b37c9b1

Patch https://git.kernel.org/stable/c/8c7e2141fb89c620ab4e41512e262fbf25b8260d

Patch https://git.kernel.org/stable/c/c656d04247a2654ede5cead2ecbf83431dad5261

Patch https://git.kernel.org/stable/c/e498b504f8c81b07efab9febf8503448de4dc9cf

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low-risk

Severity 18/34 · Moderate

Exploitability 0/34 · Minimal

Exposure 5/34 · Minimal