Re: [PATCH 4.9+] s390/mm: Check for valid vma before zapping in gmap_discard

On Thu, Nov 08, 2018 at 09:41:00AM +0100, Janosch Frank wrote:

From: Janosch Frank frankja@de.ibm.com

Userspace could have munmapped the area before doing unmapping from the gmap. This would leave us with a valid vmaddr, but an invalid vma from which we would try to zap memory.

Let's check before using the vma.

Fixes: 1e133ab296f3 ("s390/mm: split arch/s390/mm/pgtable.c") Signed-off-by: Janosch Frank frankja@linux.ibm.com Reviewed-by: David Hildenbrand david@redhat.com Reported-by: Dan Carpenter dan.carpenter@oracle.com CC: stable@vger.kernel.org # 4.6+

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arch/s390/mm/gmap.c | 2 ++ 1 file changed, 2 insertions(+)

Please always include the upstream git commit id so that I have a clue as to what it is when doing the backport.

thanks,

greg k-h