CVE-2024-46838

userfaultfd: don't BUG_ON() if khugepaged yanks our page table

Published Sep 27, 2024 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

userfaultfd: don't BUG_ON() if khugepaged yanks our page table

Since khugepaged was changed to allow retracting page tables in file
mappings without holding the mmap lock, these BUG_ON()s are wrong - get
rid of them.

We could also remove the preceding "if (unlikely(...))" block, but then we
could reach pte_offset_map_lock() with transhuge pages not just for file
mappings but also for anonymous mappings - which would probably be fine
but I think is not necessarily expected.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-7154-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7155-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-7156-1 Linux kernel (GKE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7154-2 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7196-1 Linux kernel (Azure) vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-362
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.11:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.11:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.11:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.11:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.11:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.11:rc6:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: userfaultfd: don't BUG_ON() if khugepaged yanks our page table Since khugepaged was changed to allow retracting page tables in file mappings without holding the mmap lock, these BUG_ON()s are wrong - get rid of them. We could also remove the preceding "if (unlikely(...))" block, but then we could reach pte_offset_map_lock() with transhuge pages not just for file mappings but also for anonymous mappings - which would probably be fine but I think is not necessarily expected.
Title userfaultfd: don't BUG_ON() if khugepaged yanks our page table
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
May 11, 2026, 8:37 PM
Reserved
Sep 11, 2024, 3:12 PM
Status
Analyzed
Published
Sep 27, 2024, 1:15 PM
Modified
Jun 17, 2026, 7:56 AM
Severity
Moderate
Public date
Sep 27, 2024, 12:00 AM