The patch titled
Subject: userfaultfd: non-cooperative: robustness check
has been added to the -mm tree. Its filename is
userfaultfd-non-cooperative-robustness-check.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-non-cooperative-robustness-check.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-non-cooperative-robustness-check.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject: userfaultfd: non-cooperative: robustness check
Similar to the handle_userfault() case, also make sure to never
attempt to send any event past the PF_EXITING point of no return.
This is purely a robustness check.
Link: http://lkml.kernel.org/r/20170224181957.19736-3-aarcange@xxxxxxxxxx
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff -puN fs/userfaultfd.c~userfaultfd-non-cooperative-robustness-check fs/userfaultfd.c
--- a/fs/userfaultfd.c~userfaultfd-non-cooperative-robustness-check
+++ a/fs/userfaultfd.c
@@ -529,8 +529,13 @@ out:
static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
struct userfaultfd_wait_queue *ewq)
{
- int ret = 0;
+ int ret;
+ ret = -1;
+ if (WARN_ON_ONCE(current->flags & PF_EXITING))
+ goto out;
+
+ ret = 0;
ewq->ctx = ctx;
init_waitqueue_entry(&ewq->wq, current);
@@ -565,7 +570,7 @@ static int userfaultfd_event_wait_comple
* ctx may go away after this if the userfault pseudo fd is
* already released.
*/
-
+out:
userfaultfd_ctx_put(ctx);
return ret;
}
_
Patches currently in -mm which might be from aarcange@xxxxxxxxxx are
userfaultfd-shmem-__do_fault-requires-vm_fault_nopage.patch
userfaultfd-non-cooperative-rollback-userfaultfd_exit.patch
userfaultfd-non-cooperative-robustness-check.patch
userfaultfd-non-cooperative-release-all-ctx-in-dup_userfaultfd_complete.patch
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