Messages in this thread | | | Date | Tue, 19 Jun 2018 21:32:00 -0700 | From | Joel Fernandes <> | Subject | Re: [PATCH 2/2 v2] staging: android: ashmem: Fix mmap size validation |
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On Tue, Jun 19, 2018 at 05:57:35PM -0700, Alistair Strachan wrote: > The ashmem driver did not check that the size/offset of the vma passed > to its .mmap() function was not larger than the ashmem object being > mapped. This could cause mmap() to succeed, even though accessing parts > of the mapping would later fail with a segmentation fault. > > Ensure an error is returned by the ashmem_mmap() function if the vma > size is larger than the ashmem object size. This enables safer handling > of the problem in userspace. > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Arve Hjønnevåg <arve@android.com> > Cc: Todd Kjos <tkjos@android.com> > Cc: Martijn Coenen <maco@android.com> > Cc: devel@driverdev.osuosl.org > Cc: linux-kernel@vger.kernel.org > Cc: kernel-team@android.com > Cc: Joel Fernandes <joel@joelfernandes.org> > Signed-off-by: Alistair Strachan <astrachan@google.com> > --- > v2: Removed unnecessary use of unlikely() macro > > drivers/staging/android/ashmem.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c > index c6386e4f5c9b..e392358ec244 100644 > --- a/drivers/staging/android/ashmem.c > +++ b/drivers/staging/android/ashmem.c > @@ -366,6 +366,12 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) > goto out; > } > > + /* requested mapping size larger than object size */ > + if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) { > + ret = -EINVAL; > + goto out; > + } > +
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
thanks,
- Joel
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