From 6a2ba1bf8f99377d4cee3742b92a0212f76c0e40 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 7 Feb 2023 17:07:50 +0800 Subject: [PATCH] hugetlbfs: fix off-by-one error in hugetlb_vmdelete_list() mainline inclusion from mainline-v6.2-rc1 commit d6aba4c8e20d4d2bf65d589953f6d891c178f3a3 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6BE56 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.2-rc4&id=d6aba4c8e20d4d2bf65d589953f6d891c178f3a3 -------------------------------- Pass "end - 1" instead of "end" when walking the interval tree in hugetlb_vmdelete_list() to fix an inclusive vs. exclusive bug. The two callers that pass a non-zero "end" treat it as exclusive, whereas the interval tree iterator expects an inclusive "last". E.g. punching a hole in a file that precisely matches the size of a single hugepage, with a vma starting right on the boundary, will result in unmap_hugepage_range() being called twice, with the second call having start==end. The off-by-one error doesn't cause functional problems as __unmap_hugepage_range() turns into a massive nop due to short-circuiting its for-loop on "address < end". But, the mmu_notifier invocations to invalid_range_{start,end}() are passed a bogus zero-sized range, which may be unexpected behavior for secondary MMUs. The bug was exposed by commit ed922739c919 ("KVM: Use interval tree to do fast hva lookup in memslots"), currently queued in the KVM tree for 5.17, which added a WARN to detect ranges with start==end. Link: https://lkml.kernel.org/r/20211228234257.1926057-1-seanjc@google.com Fixes: 1bfad99ab425 ("hugetlbfs: hugetlb_vmtruncate_list() needs to take a range to delete") Signed-off-by: Sean Christopherson Reported-by: syzbot+4e697fe80a31aa7efe21@syzkaller.appspotmail.com Reviewed-by: Mike Kravetz Cc: Paolo Bonzini Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Li Lingfeng Reviewed-by: Zhihao Cheng Reviewed-by: Zhang Yi Signed-off-by: Jialin Zhang (cherry picked from commit 787b77fac411c2437b0e73c307a21f715ba35187) --- fs/hugetlbfs/inode.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 379aa008514d..cfdd8cffe6d7 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -472,10 +472,11 @@ hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end) struct vm_area_struct *vma; /* - * end == 0 indicates that the entire range after - * start should be unmapped. + * end == 0 indicates that the entire range after start should be + * unmapped. Note, end is exclusive, whereas the interval tree takes + * an inclusive "last". */ - vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) { + vma_interval_tree_foreach(vma, root, start, end ? end - 1 : ULONG_MAX) { unsigned long v_offset; unsigned long v_end; -- GitLab