From: Mike Rapoport <rppt@linux.vnet.ibm.com>
Date: Wed, 2 Aug 2017 13:32:15 -0700
Subject: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone
References: bnc#1060662
Patch-mainline: v4.12.6
Git-commit: 9d95aa4bada24be35bb94827a55e1d6e243d866e
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-rppt@linux.vnet.ibm.com
Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone")
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/userfaultfd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 1d622f276e3a..c0b2787bdcd4 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1645,6 +1645,8 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
uffdio_zeropage.range.len);
mmput(ctx->mm);
+ } else {
+ return -ENOSPC;
}
if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage)))
return -EFAULT;
--
2.14.2