| 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-2024-42316: mm/mglru: fix div-by-zero in vmpressure_calc_level() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm/mglru: fix div-by-zero in vmpressure_calc_level() |
| |
| evict_folios() uses a second pass to reclaim folios that have gone through |
| page writeback and become clean before it finishes the first pass, since |
| folio_rotate_reclaimable() cannot handle those folios due to the |
| isolation. |
| |
| The second pass tries to avoid potential double counting by deducting |
| scan_control->nr_scanned. However, this can result in underflow of |
| nr_scanned, under a condition where shrink_folio_list() does not increment |
| nr_scanned, i.e., when folio_trylock() fails. |
| |
| The underflow can cause the divisor, i.e., scale=scanned+reclaimed in |
| vmpressure_calc_level(), to become zero, resulting in the following crash: |
| |
| [exception RIP: vmpressure_work_fn+101] |
| process_one_work at ffffffffa3313f2b |
| |
| Since scan_control->nr_scanned has no established semantics, the potential |
| double counting has minimal risks. Therefore, fix the problem by not |
| deducting scan_control->nr_scanned in evict_folios(). |
| |
| The Linux kernel CVE team has assigned CVE-2024-42316 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.1 with commit 359a5e1416caaf9ce28396a65ed3e386cc5de663 and fixed in 6.1.103 with commit 8de7bf77f21068a5f602bb1e59adbc5ab533509d |
| Issue introduced in 6.1 with commit 359a5e1416caaf9ce28396a65ed3e386cc5de663 and fixed in 6.6.44 with commit d6510f234c7d117790397f9bb150816b0a954a04 |
| Issue introduced in 6.1 with commit 359a5e1416caaf9ce28396a65ed3e386cc5de663 and fixed in 6.10.3 with commit a39e38be632f0e1c908d70d1c9cd071c03faf895 |
| Issue introduced in 6.1 with commit 359a5e1416caaf9ce28396a65ed3e386cc5de663 and fixed in 6.11 with commit 8b671fe1a879923ecfb72dda6caf01460dd885ef |
| |
| 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-2024-42316 |
| 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: |
| mm/vmscan.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/8de7bf77f21068a5f602bb1e59adbc5ab533509d |
| https://git.kernel.org/stable/c/d6510f234c7d117790397f9bb150816b0a954a04 |
| https://git.kernel.org/stable/c/a39e38be632f0e1c908d70d1c9cd071c03faf895 |
| https://git.kernel.org/stable/c/8b671fe1a879923ecfb72dda6caf01460dd885ef |
