UBUNTU-CVE-2024-36881
In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: reset ptes when close() for wr-protected ones Userfaultfd unregister includes a step to remove wr-protect bits from all the relevant pgtable entries, but that only covered an explicit UFFDIO_UNREGISTER ioctl, not a close() on the userfaultfd itself. Cover that too. This fixes a WARN trace. The only user visible side effect is the user can observe leftover wr-protect bits even if the user close()ed on an userfaultfd when releasing the last reference of it. However hopefully that should be harmless, and nothing bad should happen even if so. This change is now more important after the recent page-table-check patch we merged in mm-unstable (446dd9ad37d0 ("mm/page_table_check: support userfault wr-protect entries")), as we'll do sanity check on uffd-wp bits without vma context. So it's better if we can 100% guarantee no uffd-wp bit leftovers, to make sure each report will be valid.
02 / AFFECTED SOFTWARE
Affected packages
29 explicit affected versions
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37 explicit affected versions
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6 explicit affected versions
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7 explicit affected versions
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23 explicit affected versions
14 explicit affected versions
3 explicit affected versions
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3 explicit affected versions
3 explicit affected versions
26 explicit affected versions
12 explicit affected versions
44 explicit affected versions
1 explicit affected versions
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4 explicit affected versions
16 explicit affected versions
9 explicit affected versions
12 explicit affected versions
13 explicit affected versions
7 explicit affected versions
9 explicit affected versions
5 explicit affected versions
13 explicit affected versions
7 explicit affected versions
10 explicit affected versions
14 explicit affected versions
18 explicit affected versions
3 explicit affected versions
16 explicit affected versions
43 explicit affected versions
4 explicit affected versions
11 explicit affected versions
35 explicit affected versions
12 explicit affected versions
13 explicit affected versions
6 explicit affected versions
12 explicit affected versions
50 explicit affected versions
11 explicit affected versions
12 explicit affected versions
27 explicit affected versions
12 explicit affected versions
7 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: reset ptes when close() for wr-protected ones Userfaultfd unregister includes a step to remove wr-protect bits from all the relevant pgtable entries, but that only covered an explicit UFFDIO_UNREGISTER ioctl, not a close() on the userfaultfd itself. Cover that too. This fixes a WARN trace. The only user visible side effect is the user can observe leftover wr-protect bits even if the user close()ed on an userfaultfd when releasing the last reference of it. However hopefully that should be harmless, and nothing bad should happen even if so. This change is now more important after the recent page-table-check patch we merged in mm-unstable (446dd9ad37d0 ("mm/page_table_check: support userfault wr-protect entries")), as we'll do sanity check on uffd-wp bits without vma context. So it's better if we can 100% guarantee no uffd-wp bit leftovers, to make sure each report will be valid.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/c88033efe9a391e72ba6b5df4b01d6e628f4e734
- https://git.kernel.org/stable/c/377f3a9a3d032a52325a5b110379a25dd1ab1931
- https://git.kernel.org/stable/c/8d8b68a5b0c9fb23d37df06bb273ead38fd5a29d
- https://git.kernel.org/stable/c/c88033efe9a391e72ba6b5df4b01d6e628f4e734
- https://ubuntu.com/security/CVE-2024-36881
- https://ubuntu.com/security/notices/USN-6949-1
- https://ubuntu.com/security/notices/USN-6949-2
- https://ubuntu.com/security/notices/USN-6952-1
- https://ubuntu.com/security/notices/USN-6952-2
- https://ubuntu.com/security/notices/USN-6955-1
- https://www.cve.org/CVERecord?id=CVE-2024-36881