CVE-2026-80785: fbdev: serialize mode sysfs access with lock_fb_info()
fbdev: serialize mode sysfs access with lockfbinfo()
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
In the Linux kernel fbdev sysfs mode handling, serialize show_mode(), show_modes(), and store_mode() with store_modes() by taking lock_fb_info(); have store_modes() hold lock_fb_info() while replacing the modelist and freeing the old one; split activate() into a _locked variant and hold the locks across the modelist walk, mode conversion, activation, and fb_info->mode assignment; copy the mode to the stack and format it after dropping the lock in show_mode().
Event History
Frequently Asked Questions
What conditions are required to trigger the issue?
The vulnerable path requires concurrent access to framebuffer mode sysfs operations. In particular, show_mode(), show_modes(), or store_mode() must race with store_modes() replacing and freeing the framebuffer modelist.
What can the race cause?
A concurrent operation can dereference a freed modelist entry or save a stale freed pointer in fb_info->mode. This is a use-after-free condition involving framebuffer mode data.
How can I tell whether a system is affected?
Assess the kernel source or applied stable commits for the locking changes to show_mode(), show_modes(), and store_mode() using lock_fb_info(). The referenced stable commits contain the resolved implementation.