UBUNTU-CVE-2026-80785: Low severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: fbdev: serialize mode sysfs access with lockfbinfo() showmode(), showmodes(), and storemode() access fbinfo->modelist and fbinfo->mode without holding lockfbinfo(). storemodes() takes lockfbinfo() while replacing the modelist and freeing the old one. A concurrent reader or writer can load a pointer to an old modelist entry before storemodes() frees it, then dereference freed memory or store a stale freed pointer in fbinfo->mode. Take lockfbinfo() in showmode(), showmodes(), and storemode() to serialize with storemodes(). In showmode(), copy the mode to the stack and format after dropping the lock. In storemode(), split activate() into a locked variant to avoid double-locking, and hold the locks for the modelist walk, mode conversion, activation, and fbinfo->mode assignment together.
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
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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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
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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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 fbdev, serialize show_mode(), show_modes(), and store_mode() with lock_fb_info(); in show_mode(), copy the mode to the stack before dropping the lock and formatting it; in store_mode(), use a _locked activate() variant and hold the locks across the modelist walk, mode conversion, activation, and fb_info->mode assignment.