| 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-2024-27022: fork: defer linking file vma until vma is fully initialized |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| fork: defer linking file vma until vma is fully initialized |
| |
| Thorvald reported a WARNING [1]. And the root cause is below race: |
| |
| CPU 1 CPU 2 |
| fork hugetlbfs_fallocate |
| dup_mmap hugetlbfs_punch_hole |
| i_mmap_lock_write(mapping); |
| vma_interval_tree_insert_after -- Child vma is visible through i_mmap tree. |
| i_mmap_unlock_write(mapping); |
| hugetlb_dup_vma_private -- Clear vma_lock outside i_mmap_rwsem! |
| i_mmap_lock_write(mapping); |
| hugetlb_vmdelete_list |
| vma_interval_tree_foreach |
| hugetlb_vma_trylock_write -- Vma_lock is cleared. |
| tmp->vm_ops->open -- Alloc new vma_lock outside i_mmap_rwsem! |
| hugetlb_vma_unlock_write -- Vma_lock is assigned!!! |
| i_mmap_unlock_write(mapping); |
| |
| hugetlb_dup_vma_private() and hugetlb_vm_op_open() are called outside |
| i_mmap_rwsem lock while vma lock can be used in the same time. Fix this |
| by deferring linking file vma until vma is fully initialized. Those vmas |
| should be initialized first before they can be used. |
| |
| The Linux kernel CVE team has assigned CVE-2024-27022 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.1 with commit 8d9bfb2608145cf3e408428c224099e1585471af and fixed in 6.8.8 with commit abdb88dd272bbeb93efe01d8e0b7b17e24af3a34 |
| Issue introduced in 6.1 with commit 8d9bfb2608145cf3e408428c224099e1585471af and fixed in 6.9 with commit 35e351780fa9d8240dd6f7e4f245f9ea37e96c19 |
| |
| 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-2024-27022 |
| 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: |
| kernel/fork.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/abdb88dd272bbeb93efe01d8e0b7b17e24af3a34 |
| https://git.kernel.org/stable/c/35e351780fa9d8240dd6f7e4f245f9ea37e96c19 |
