CVE-2021-47641

video: fbdev: cirrusfb: check pixclock to avoid divide by zero

State: Published
Severity: 5.5 Medium
Published: Feb 26, 2025
Updated: May 11, 2026
Reserved: Feb 26, 2025

Description

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

Scores

CVSS	Score	Vector	Source
3.1	5.5 Medium	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H	CISA-ADP

Weaknesses

CWE-369 Divide By Zero

Affected Products

Product	Versions
LinuxLinux	1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before c656d04247a2654ede5cead2ecbf83431dad5261Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 1d3fb46439ad4e8f0c5739eb33d1875ac9e0f135Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 40b13e3d85744210db13457785646634e2d056bdAffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 53a2088a396cfa1da92690a1da289634cd73bf0dAffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 8c7e2141fb89c620ab4e41512e262fbf25b8260dAffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 6fe23ff94e7840097202e85c148688940b37c9b1Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 45800c42ef000f417270bcfc08630e42486fca99Affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before e498b504f8c81b07efab9febf8503448de4dc9cfAffected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 5c6f402bdcf9e7239c6bc7087eda71ac99b31379Affected
LinuxLinux	2.6.12Affected before 2.6.12Not affected 4.9.311 through 4.9.Not affected 4.14.276 through 4.14.Not affected 4.19.238 through 4.19.Not affected 5.4.189 through 5.4.Not affected 5.10.110 through 5.10.Not affected 5.15.33 through 5.15.Not affected 5.16.19 through 5.16.Not affected 5.17.2 through 5.17.Not affected 5.18 and laterNot affected

Product

Versions

LinuxLinux

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before c656d04247a2654ede5cead2ecbf83431dad5261Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 1d3fb46439ad4e8f0c5739eb33d1875ac9e0f135Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 40b13e3d85744210db13457785646634e2d056bdAffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 53a2088a396cfa1da92690a1da289634cd73bf0dAffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 8c7e2141fb89c620ab4e41512e262fbf25b8260dAffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 6fe23ff94e7840097202e85c148688940b37c9b1Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 45800c42ef000f417270bcfc08630e42486fca99Affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before e498b504f8c81b07efab9febf8503448de4dc9cfAffected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to before 5c6f402bdcf9e7239c6bc7087eda71ac99b31379Affected

LinuxLinux

2.6.12Affected
before 2.6.12Not affected
4.9.311 through 4.9.*Not affected
4.14.276 through 4.14.*Not affected
4.19.238 through 4.19.*Not affected
5.4.189 through 5.4.*Not affected
5.10.110 through 5.10.*Not affected
5.15.33 through 5.15.*Not affected
5.16.19 through 5.16.*Not affected
5.17.2 through 5.17.*Not affected
5.18 and laterNot affected

References

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