| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-36881: mm/userfaultfd: reset ptes when close() for wr-protected ones |
| |
| Description |
| =========== |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2024-36881 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.0 with commit f369b07c861435bd812a9d14493f71b34132ed6f and fixed in 6.6.31 with commit 377f3a9a3d032a52325a5b110379a25dd1ab1931 |
| Issue introduced in 6.0 with commit f369b07c861435bd812a9d14493f71b34132ed6f and fixed in 6.8.10 with commit 8d8b68a5b0c9fb23d37df06bb273ead38fd5a29d |
| Issue introduced in 6.0 with commit f369b07c861435bd812a9d14493f71b34132ed6f and fixed in 6.9 with commit c88033efe9a391e72ba6b5df4b01d6e628f4e734 |
| Issue introduced in 5.19.6 with commit 3e2747c3ddfa717697c3cc2aa6ab989e48d6587d |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-36881 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/userfaultfd.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/377f3a9a3d032a52325a5b110379a25dd1ab1931 |
| https://git.kernel.org/stable/c/8d8b68a5b0c9fb23d37df06bb273ead38fd5a29d |
| https://git.kernel.org/stable/c/c88033efe9a391e72ba6b5df4b01d6e628f4e734 |
