| 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-2024-42233: filemap: replace pte_offset_map() with pte_offset_map_nolock() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| filemap: replace pte_offset_map() with pte_offset_map_nolock() |
| |
| The vmf->ptl in filemap_fault_recheck_pte_none() is still set from |
| handle_pte_fault(). But at the same time, we did a pte_unmap(vmf->pte). |
| After a pte_unmap(vmf->pte) unmap and rcu_read_unlock(), the page table |
| may be racily changed and vmf->ptl maybe fails to protect the actual page |
| table. Fix this by replacing pte_offset_map() with |
| pte_offset_map_nolock(). |
| |
| As David said, the PTL pointer might be stale so if we continue to use |
| it infilemap_fault_recheck_pte_none(), it might trigger UAF. Also, if |
| the PTL fails, the issue fixed by commit 58f327f2ce80 ("filemap: avoid |
| unnecessary major faults in filemap_fault()") might reappear. |
| |
| The Linux kernel CVE team has assigned CVE-2024-42233 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.9 with commit 58f327f2ce80f9c7b4a70e9cf017ae8810d44a20 and fixed in 6.9.10 with commit 6a6c2aec1a89506595801b4cf7e8eef035f33748 |
| Issue introduced in 6.9 with commit 58f327f2ce80f9c7b4a70e9cf017ae8810d44a20 and fixed in 6.10 with commit 24be02a42181f0707be0498045c4c4b13273b16d |
| |
| 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-2024-42233 |
| 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/filemap.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/6a6c2aec1a89506595801b4cf7e8eef035f33748 |
| https://git.kernel.org/stable/c/24be02a42181f0707be0498045c4c4b13273b16d |
