UBUNTU-CVE-2026-93216: Low severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: mm/pageowner: use memcgdata snapshot to avoid TOCTOU in printpageownermemcg() printpageownermemcg() reads page->memcgdata via READONCE() at the start to guard against tail pages and NULL data. However, it later re-reads page->memcgdata locklessly in two places: 1: pagememcgcheck(page) 2: PageMemcgKmem(page) (via foliomemcgkmem(), which includes VMBUGON assertions for tail pages and MEMCGDATAOBJEXTS) If the page is concurrently freed and reallocated as a THP tail page or slab page between these calls, the VMBUGON assertions can trigger on CONFIGDEBUGVM=y builds, crashing the kernel. Fix both TOCTOU issues by using the memcgdata snapshot throughout.
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
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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
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
Modify print_page_owner_memcg() to use the initial memcg_data snapshot throughout, including for page_memcg_check(page) and PageMemcgKmem(page) via folio_memcg_kmem(), instead of re-reading page->memcg_data locklessly.