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| author | Lokesh Gidra <lokeshgidra@google.com> | 2024-01-17 14:37:29 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-03-01 13:06:08 +0100 |
| commit | 4a41f41c928d1c62da9fcc87ad349c201d91a43e (patch) | |
| tree | 08b2545294bdaff51949c18d7e319dc91cf1f80b | |
| parent | b06dec684e11ea944d896ac78cec1602e5157eb8 (diff) | |
| download | linux-stable-4a41f41c928d1c62da9fcc87ad349c201d91a43e.tar.gz linux-stable-4a41f41c928d1c62da9fcc87ad349c201d91a43e.tar.bz2 linux-stable-4a41f41c928d1c62da9fcc87ad349c201d91a43e.zip | |
userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb
commit 67695f18d55924b2013534ef3bdc363bc9e14605 upstream.
In mfill_atomic_hugetlb(), mmap_changing isn't being checked
again if we drop mmap_lock and reacquire it. When the lock is not held,
mmap_changing could have been incremented. This is also inconsistent
with the behavior in mfill_atomic().
Link: https://lkml.kernel.org/r/20240117223729.1444522-1-lokeshgidra@google.com
Fixes: df2cc96e77011 ("userfaultfd: prevent non-cooperative events vs mcopy_atomic races")
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nicolas Geoffray <ngeoffray@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | mm/userfaultfd.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index aae19c29bcfa..dcca7788222a 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -179,6 +179,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, + bool *mmap_changing, bool zeropage) { int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; @@ -310,6 +311,15 @@ retry: goto out; } down_read(&dst_mm->mmap_sem); + /* + * If memory mappings are changing because of non-cooperative + * operation (e.g. mremap) running in parallel, bail out and + * request the user to retry later + */ + if (mmap_changing && READ_ONCE(*mmap_changing)) { + err = -EAGAIN; + break; + } dst_vma = NULL; goto retry; @@ -391,6 +401,7 @@ extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, + bool *mmap_changing, bool zeropage); #endif /* CONFIG_HUGETLB_PAGE */ @@ -508,7 +519,8 @@ retry: */ if (is_vm_hugetlb_page(dst_vma)) return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, - src_start, len, zeropage); + src_start, len, mmap_changing, + zeropage); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; |