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| author | Mike Kravetz <mike.kravetz@oracle.com> | 2017-09-06 16:20:55 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-06 17:27:26 -0700 |
| commit | dba58d3b8c5045ad89c1c95d33d01451e3964db7 (patch) | |
| tree | 39a5693fa2844a073a85be7ad9482fc4d55dfb51 /mm/mremap.c | |
| parent | 10903027948d768d9639b31e9a555802e2dabafc (diff) | |
| download | linux-0-day-dba58d3b8c5045ad89c1c95d33d01451e3964db7.tar.gz linux-0-day-dba58d3b8c5045ad89c1c95d33d01451e3964db7.tar.xz | |
mm/mremap: fail map duplication attempts for private mappings
mremap will attempt to create a 'duplicate' mapping if old_size == 0 is
specified. In the case of private mappings, mremap will actually create
a fresh separate private mapping unrelated to the original. This does
not fit with the design semantics of mremap as the intention is to
create a new mapping based on the original.
Therefore, return EINVAL in the case where an attempt is made to
duplicate a private mapping. Also, print a warning message (once) if
such an attempt is made.
Link: http://lkml.kernel.org/r/cb9d9f6a-7095-582f-15a5-62643d65c736@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mremap.c')
| -rw-r--r-- | mm/mremap.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index 3f23715d3c692..7395564daa6c2 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -384,6 +384,19 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, if (!vma || vma->vm_start > addr) return ERR_PTR(-EFAULT); + /* + * !old_len is a special case where an attempt is made to 'duplicate' + * a mapping. This makes no sense for private mappings as it will + * instead create a fresh/new mapping unrelated to the original. This + * is contrary to the basic idea of mremap which creates new mappings + * based on the original. There are no known use cases for this + * behavior. As a result, fail such attempts. + */ + if (!old_len && !(vma->vm_flags & (VM_SHARED | VM_MAYSHARE))) { + pr_warn_once("%s (%d): attempted to duplicate a private mapping with mremap. This is not supported.\n", current->comm, current->pid); + return ERR_PTR(-EINVAL); + } + if (is_vm_hugetlb_page(vma)) return ERR_PTR(-EINVAL); |