From bippy-7d53e8ef8be4 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman To: Reply-to: , 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 8d9bfb260814 and fixed in 6.1.90 with commit 0c42f7e039ab Issue introduced in 6.1 with commit 8d9bfb260814 and fixed in 6.1.95 with commit 04b0c4191234 Issue introduced in 6.1 with commit 8d9bfb260814 and fixed in 6.6.30 with commit cec11fa2eb51 Issue introduced in 6.1 with commit 8d9bfb260814 and fixed in 6.6.35 with commit dd782da47076 Issue introduced in 6.1 with commit 8d9bfb260814 and fixed in 6.8.8 with commit abdb88dd272b Issue introduced in 6.1 with commit 8d9bfb260814 and fixed in 6.9 with commit 35e351780fa9 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/0c42f7e039aba3de6d7dbf92da708e2b2ecba557 https://git.kernel.org/stable/c/04b0c41912349aff11a1bbaef6a722bd7fbb90ac https://git.kernel.org/stable/c/cec11fa2eb512ebe3a459c185f4aca1d44059bbf https://git.kernel.org/stable/c/dd782da470761077f4d1120e191f1a35787cda6e https://git.kernel.org/stable/c/abdb88dd272bbeb93efe01d8e0b7b17e24af3a34 https://git.kernel.org/stable/c/35e351780fa9d8240dd6f7e4f245f9ea37e96c19