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Suren Baghdasaryan authored
When ashmem file is mmapped, the resulting vma->vm_file points to the backing shmem file with the generic fops that do not check ashmem permissions like fops of ashmem do. If an mremap is done on the ashmem region, then the permission checks will be skipped. Fix that by disallowing mapping operation on the backing shmem file. Reported-by:
Jann Horn <jannh@google.com> Signed-off-by:
Suren Baghdasaryan <surenb@google.com> Cc: stable <stable@vger.kernel.org> # 4.4,4.9,4.14,4.18,5.4 Signed-off-by:
Todd Kjos <tkjos@google.com> Reviewed-by:
Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lore.kernel.org/r/20200127235616.48920-1-tkjos@google.comSigned-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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