[PATCH 4.12 020/106] userfaultfd_zeropage: return -ENOSPC in case mm has gone

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

--

From: Mike Rapoport 

commit 9d95aa4bada24be35bb94827a55e1d6e243d866e upstream.

In the non-cooperative userfaultfd case, the process exit may race with
outstanding mcopy_atomic called by the uffd monitor.  Returning -ENOSPC
instead of -EINVAL when mm is already gone will allow uffd monitor to
distinguish this case from other error conditions.

Unfortunately I overlooked userfaultfd_zeropage when updating
userfaultd_copy().

Link: 
http://lkml.kernel.org/r/1501136819-21857-1-git-send-email-r...@linux.vnet.ibm.com
Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone")
Signed-off-by: Mike Rapoport 
Cc: Andrea Arcangeli 
Cc: "Dr. David Alan Gilbert" 
Cc: Pavel Emelyanov 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman 

---
 fs/userfaultfd.c |2 ++
 1 file changed, 2 insertions(+)

--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1645,6 +1645,8 @@ static int userfaultfd_zeropage(struct u
ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
 uffdio_zeropage.range.len);
mmput(ctx->mm);
+   } else {
+   return -ENOSPC;
}
if (unlikely(put_user(ret, _uffdio_zeropage->zeropage)))
return -EFAULT;

[PATCH 4.12 020/106] userfaultfd_zeropage: return -ENOSPC in case mm has gone

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

--

From: Mike Rapoport 

commit 9d95aa4bada24be35bb94827a55e1d6e243d866e upstream.

In the non-cooperative userfaultfd case, the process exit may race with
outstanding mcopy_atomic called by the uffd monitor.  Returning -ENOSPC
instead of -EINVAL when mm is already gone will allow uffd monitor to
distinguish this case from other error conditions.

Unfortunately I overlooked userfaultfd_zeropage when updating
userfaultd_copy().

Link: 
http://lkml.kernel.org/r/1501136819-21857-1-git-send-email-r...@linux.vnet.ibm.com
Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone")
Signed-off-by: Mike Rapoport 
Cc: Andrea Arcangeli 
Cc: "Dr. David Alan Gilbert" 
Cc: Pavel Emelyanov 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman 

---
 fs/userfaultfd.c |2 ++
 1 file changed, 2 insertions(+)

--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1645,6 +1645,8 @@ static int userfaultfd_zeropage(struct u
ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
 uffdio_zeropage.range.len);
mmput(ctx->mm);
+   } else {
+   return -ENOSPC;
}
if (unlikely(put_user(ret, _uffdio_zeropage->zeropage)))
return -EFAULT;