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CVE-2026-98505

Linux: mm/damon/vaddr: avoid hw-driven pte updates during damon_hugetlb_mkold()

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.20%Chance of exploitation activity in the next 30 days, higher than 9% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in7ed1062d154ec2401f2c894fd6858598bb1160b6Also 00457981327c80bcc56e07d4714fe189337a19fa, 6e74ffc9ecf6ec24eee117150da78a1102be74c5 and 1 moreCVE List
Published18 Oct 2026Updated 21 Oct 2026CVE List

What fixes it

  • 7ed1062d154ec2401f2c894fd6858598bb1160b6LinuxCVE List
  • 00457981327c80bcc56e07d4714fe189337a19faLinuxCVE List
  • 6e74ffc9ecf6ec24eee117150da78a1102be74c5LinuxCVE List
  • 39c0ceedd54557bdc1542de08d22b2ed33e534e4LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

In the Linux kernel, the following vulnerability has been resolved:

mm/damon/vaddr: avoid hw-driven pte updates during damon_hugetlb_mkold()

damon_hugetlb_mkold() reads the page table entry into a local variable, unsets the accessed bit in the variable, and updates the page table entry with the updated variable value. If hardware updates the same page table entry in parallel, the hw updates could be lost. For example, hardware-updated dirty bits might be lost.

Avoid the parallel updates by clearing the page table entry when reading it together, using huge_ptep_get_and_clear(). If a parallel write to the memory is made after the clearing, the hw will see the page table entry is cleared, trigger page fault and wait until it is handled. The page fault handling will wait for damon_hugetlb_mkold() due to the page table lock.

Because hugetlbfs is an in-memory file system and hugetlb pages cannot be reclaimed, no critical issue is expected to my best knowledge. But definitely this is a nasty bug that should be fixed sooner rather than later.

The issue was discovered [1] by Sashiko.

Text from CVE List

Affected versions 12

  • Linuxaffected: 49f4203aae06ba9d67b500c90339b262b0a52637 before 7ed1062d154ec2401f2c894fd6858598bb1160b6CVE List
  • Linuxaffected: 49f4203aae06ba9d67b500c90339b262b0a52637 before 00457981327c80bcc56e07d4714fe189337a19faCVE List
  • Linuxaffected: 49f4203aae06ba9d67b500c90339b262b0a52637 before e59cb7eda7c06334a0faf5aa44adb6acf2a1287aCVE List
  • Linuxaffected: 49f4203aae06ba9d67b500c90339b262b0a52637 before 6e74ffc9ecf6ec24eee117150da78a1102be74c5CVE List
  • Linuxaffected: 49f4203aae06ba9d67b500c90339b262b0a52637 before 39c0ceedd54557bdc1542de08d22b2ed33e534e4CVE List
  • Linuxaffected: 5.17CVE List
  • Linuxunaffected: all versions before 5.17CVE List
  • Linuxunaffected: 6.6.160 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.55 through 6.18.*CVE List
  • Linuxunaffected: 7.2.9 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5