| 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-2024-35872: mm/secretmem: fix GUP-fast succeeding on secretmem folios |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm/secretmem: fix GUP-fast succeeding on secretmem folios |
| |
| folio_is_secretmem() currently relies on secretmem folios being LRU |
| folios, to save some cycles. |
| |
| However, folios might reside in a folio batch without the LRU flag set, or |
| temporarily have their LRU flag cleared. Consequently, the LRU flag is |
| unreliable for this purpose. |
| |
| In particular, this is the case when secretmem_fault() allocates a fresh |
| page and calls filemap_add_folio()->folio_add_lru(). The folio might be |
| added to the per-cpu folio batch and won't get the LRU flag set until the |
| batch was drained using e.g., lru_add_drain(). |
| |
| Consequently, folio_is_secretmem() might not detect secretmem folios and |
| GUP-fast can succeed in grabbing a secretmem folio, crashing the kernel |
| when we would later try reading/writing to the folio, because the folio |
| has been unmapped from the directmap. |
| |
| Fix it by removing that unreliable check. |
| |
| The Linux kernel CVE team has assigned CVE-2024-35872 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.14 with commit 1507f51255c9ff07d75909a84e7c0d7f3c4b2f49 and fixed in 5.15.154 with commit 6564b014af92b677c1f07c44d7f5b595d589cf6e |
| Issue introduced in 5.14 with commit 1507f51255c9ff07d75909a84e7c0d7f3c4b2f49 and fixed in 6.1.85 with commit 9c2b4b657739ecda38e3b383354a29566955ac48 |
| Issue introduced in 5.14 with commit 1507f51255c9ff07d75909a84e7c0d7f3c4b2f49 and fixed in 6.6.26 with commit 43fad1d0284de30159661d0badfc3cbaf7e6f8f8 |
| Issue introduced in 5.14 with commit 1507f51255c9ff07d75909a84e7c0d7f3c4b2f49 and fixed in 6.8.5 with commit 201e4aaf405dfd1308da54448654053004c579b5 |
| Issue introduced in 5.14 with commit 1507f51255c9ff07d75909a84e7c0d7f3c4b2f49 and fixed in 6.9 with commit 65291dcfcf8936e1b23cfd7718fdfde7cfaf7706 |
| |
| 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-2024-35872 |
| 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/secretmem.h |
| |
| |
| 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/6564b014af92b677c1f07c44d7f5b595d589cf6e |
| https://git.kernel.org/stable/c/9c2b4b657739ecda38e3b383354a29566955ac48 |
| https://git.kernel.org/stable/c/43fad1d0284de30159661d0badfc3cbaf7e6f8f8 |
| https://git.kernel.org/stable/c/201e4aaf405dfd1308da54448654053004c579b5 |
| https://git.kernel.org/stable/c/65291dcfcf8936e1b23cfd7718fdfde7cfaf7706 |
