The quilt patch titled Subject: filemap: replace pte_offset_map() with pte_offset_map_nolock() has been removed from the -mm tree. Its filename was filemap-replace-pte_offset_map-with-pte_offset_map_nolock.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: ZhangPeng zhangpeng362@huawei.com Subject: filemap: replace pte_offset_map() with pte_offset_map_nolock() Date: Wed, 13 Mar 2024 09:29:13 +0800

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.

Link: https://lkml.kernel.org/r/20240313012913.2395414-1-zhangpeng362@huawei.com Fixes: 58f327f2ce80 ("filemap: avoid unnecessary major faults in filemap_fault()") Signed-off-by: ZhangPeng zhangpeng362@huawei.com Suggested-by: David Hildenbrand david@redhat.com Reviewed-by: David Hildenbrand david@redhat.com Cc: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Cc: "Huang, Ying" ying.huang@intel.com Cc: Hugh Dickins hughd@google.com Cc: Kefeng Wang wangkefeng.wang@huawei.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Nanyong Sun sunnanyong@huawei.com Cc: Yang Shi shy828301@gmail.com Cc: Yin Fengwei fengwei.yin@intel.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/filemap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/filemap.c~filemap-replace-pte_offset_map-with-pte_offset_map_nolock +++ a/mm/filemap.c @@ -3231,7 +3231,8 @@ static vm_fault_t filemap_fault_recheck_ if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) return 0;

- ptep = pte_offset_map(vmf->pmd, vmf->address); + ptep = pte_offset_map_nolock(vma->vm_mm, vmf->pmd, vmf->address, + &vmf->ptl); if (unlikely(!ptep)) return VM_FAULT_NOPAGE;

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Patches currently in -mm which might be from zhangpeng362@huawei.com are