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

mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0)

If an mremap() syscall with old_size=0 ends up in move_page_tables(), it
will call invalidate_range_start()/invalidate_range_end() unnecessarily,
i.e. with an empty range.

This causes a WARN in KVM's mmu_notifier. In the past, empty ranges
have been diagnosed to be off-by-one bugs, hence the WARNing. Given the
low (so far) number of unique reports, the benefits of detecting more
buggy callers seem to outweigh the cost of having to fix cases such as
this one, where userspace is doing something silly. In this particular
case, an early return from move_page_tables() is enough to fix the
issue.
History

Thu, 17 Apr 2025 05:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-193
Metrics threat_severity

Low

threat_severity

Moderate


Thu, 27 Feb 2025 01:45:00 +0000

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

Low


Wed, 26 Feb 2025 02:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0) If an mremap() syscall with old_size=0 ends up in move_page_tables(), it will call invalidate_range_start()/invalidate_range_end() unnecessarily, i.e. with an empty range. This causes a WARN in KVM's mmu_notifier. In the past, empty ranges have been diagnosed to be off-by-one bugs, hence the WARNing. Given the low (so far) number of unique reports, the benefits of detecting more buggy callers seem to outweigh the cost of having to fix cases such as this one, where userspace is doing something silly. In this particular case, an early return from move_page_tables() is enough to fix the issue.
Title mmmremap.c: avoid pointless invalidate_range_start/end on mremap(old_size=0)
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-05-04T08:29:13.921Z

Reserved: 2025-02-26T01:49:39.247Z

Link: CVE-2022-49077

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2025-02-26T07:00:45.043

Modified: 2025-02-26T07:00:45.043

Link: CVE-2022-49077

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-02-26T00:00:00Z

Links: CVE-2022-49077 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-07-12T22:01:20Z