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| author | Andrea Arcangeli <aarcange@redhat.com> | 2017-03-09 16:16:52 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-03-09 17:01:09 -0800 |
| commit | 9a69a829f9b656c2a220d65a94ecf7b5887c5da1 (patch) | |
| tree | dee2ed7716c4d6ce06f1e6762c6eb5f002b91f23 /fs/userfaultfd.c | |
| parent | dd0db88d8094a6d9d4d1fc5fcd56ab619f54ccf8 (diff) | |
| download | lwn-9a69a829f9b656c2a220d65a94ecf7b5887c5da1.tar.gz lwn-9a69a829f9b656c2a220d65a94ecf7b5887c5da1.zip | |
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@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/userfaultfd.c')
| -rw-r--r-- | fs/userfaultfd.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 16d0cc600fa9..668bbbd2e04d 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -530,8 +530,13 @@ 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); @@ -566,7 +571,7 @@ static int userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx, * ctx may go away after this if the userfault pseudo fd is * already released. */ - +out: userfaultfd_ctx_put(ctx); return ret; } |