| From bippy-1.0.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-35993: mm: turn folio_test_hugetlb into a PageType |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm: turn folio_test_hugetlb into a PageType |
| |
| The current folio_test_hugetlb() can be fooled by a concurrent folio split |
| into returning true for a folio which has never belonged to hugetlbfs. |
| This can't happen if the caller holds a refcount on it, but we have a few |
| places (memory-failure, compaction, procfs) which do not and should not |
| take a speculative reference. |
| |
| Since hugetlb pages do not use individual page mapcounts (they are always |
| fully mapped and use the entire_mapcount field to record the number of |
| mappings), the PageType field is available now that page_mapcount() |
| ignores the value in this field. |
| |
| In compaction and with CONFIG_DEBUG_VM enabled, the current implementation |
| can result in an oops, as reported by Luis. This happens since 9c5ccf2db04b |
| ("mm: remove HUGETLB_PAGE_DTOR") effectively added some VM_BUG_ON() checks |
| in the PageHuge() testing path. |
| |
| [willy@infradead.org: update vmcoreinfo] |
| |
| The Linux kernel CVE team has assigned CVE-2024-35993 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.6 with commit 9c5ccf2db04b8d7c3df363fdd4856c2b79ab2c6a and fixed in 6.6.30 with commit 2431b5f2650dfc47ce782d1ca7b02d6b3916976f |
| Issue introduced in 6.6 with commit 9c5ccf2db04b8d7c3df363fdd4856c2b79ab2c6a and fixed in 6.8.9 with commit 9fdcc5b6359dfdaa52a55033bf50e2cedd66eb32 |
| Issue introduced in 6.6 with commit 9c5ccf2db04b8d7c3df363fdd4856c2b79ab2c6a and fixed in 6.9 with commit d99e3140a4d33e26066183ff727d8f02f56bec64 |
| |
| 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-2024-35993 |
| 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: |
| include/linux/page-flags.h |
| include/trace/events/mmflags.h |
| kernel/vmcore_info.c |
| mm/hugetlb.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/2431b5f2650dfc47ce782d1ca7b02d6b3916976f |
| https://git.kernel.org/stable/c/9fdcc5b6359dfdaa52a55033bf50e2cedd66eb32 |
| https://git.kernel.org/stable/c/d99e3140a4d33e26066183ff727d8f02f56bec64 |
