tree 283b23123a0dd68166c2f8a35a59b6fd3677a9aa
parent ec9645f1a77eab98951944273754307e192e69ae
author Suren Baghdasaryan <surenb@google.com> 1580169376 -0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1582904325 +0100

staging: android: ashmem: Disallow ashmem memory from being remapped

commit 6d67b0290b4b84c477e6a2fc6e005e174d3c7786 upstream.

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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>