releases/4.14.117/rxrpc-fix-net-namespace-cleanup.patch

   1 From foo@baz Sat 04 May 2019 11:25:56 AM CEST
   2 From: David Howells <dhowells@redhat.com>
   3 Date: Tue, 30 Apr 2019 08:34:08 +0100
   4 Subject: rxrpc: Fix net namespace cleanup
   5
   6 From: David Howells <dhowells@redhat.com>
   7
   8 [ Upstream commit b13023421b5179413421333f602850914f6a7ad8 ]
   9
  10 In rxrpc_destroy_all_calls(), there are two phases: (1) make sure the
  11 ->calls list is empty, emitting error messages if not, and (2) wait for the
  12 RCU cleanup to happen on outstanding calls (ie. ->nr_calls becomes 0).
  13
  14 To avoid taking the call_lock, the function prechecks ->calls and if empty,
  15 it returns to avoid taking the lock - this is wrong, however: it still
  16 needs to go and do the second phase and wait for ->nr_calls to become 0.
  17
  18 Without this, the rxrpc_net struct may get deallocated before we get to the
  19 RCU cleanup for the last calls.  This can lead to:
  20
  21   Slab corruption (Not tainted): kmalloc-16k start=ffff88802b178000, len=16384
  22   050: 6b 6b 6b 6b 6b 6b 6b 6b 61 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkakkkkkkk
  23
  24 Note the "61" at offset 0x58.  This corresponds to the ->nr_calls member of
  25 struct rxrpc_net (which is >9k in size, and thus allocated out of the 16k
  26 slab).
  27
  28 Fix this by flipping the condition on the if-statement, putting the locked
  29 section inside the if-body and dropping the return from there.  The
  30 function will then always go on to wait for the RCU cleanup on outstanding
  31 calls.
  32
  33 Fixes: 2baec2c3f854 ("rxrpc: Support network namespacing")
  34 Signed-off-by: David Howells <dhowells@redhat.com>
  35 Signed-off-by: David S. Miller <davem@davemloft.net>
  36 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  37 ---
  38  net/rxrpc/call_object.c |   38 +++++++++++++++++++-------------------
  39  1 file changed, 19 insertions(+), 19 deletions(-)
  40
  41 --- a/net/rxrpc/call_object.c
  42 +++ b/net/rxrpc/call_object.c
  43 @@ -684,27 +684,27 @@ void rxrpc_destroy_all_calls(struct rxrp
  44
  45         _enter("");
  46
  47 -       if (list_empty(&rxnet->calls))
  48 -               return;
  49 -
  50 -       write_lock(&rxnet->call_lock);
  51 +       if (!list_empty(&rxnet->calls)) {
  52 +               write_lock(&rxnet->call_lock);
  53
  54 -       while (!list_empty(&rxnet->calls)) {
  55 -               call = list_entry(rxnet->calls.next, struct rxrpc_call, link);
  56 -               _debug("Zapping call %p", call);
  57 -
  58 -               rxrpc_see_call(call);
  59 -               list_del_init(&call->link);
  60 -
  61 -               pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n",
  62 -                      call, atomic_read(&call->usage),
  63 -                      rxrpc_call_states[call->state],
  64 -                      call->flags, call->events);
  65 +               while (!list_empty(&rxnet->calls)) {
  66 +                       call = list_entry(rxnet->calls.next,
  67 +                                         struct rxrpc_call, link);
  68 +                       _debug("Zapping call %p", call);
  69 +
  70 +                       rxrpc_see_call(call);
  71 +                       list_del_init(&call->link);
  72 +
  73 +                       pr_err("Call %p still in use (%d,%s,%lx,%lx)!\n",
  74 +                              call, atomic_read(&call->usage),
  75 +                              rxrpc_call_states[call->state],
  76 +                              call->flags, call->events);
  77 +
  78 +                       write_unlock(&rxnet->call_lock);
  79 +                       cond_resched();
  80 +                       write_lock(&rxnet->call_lock);
  81 +               }
  82
  83                 write_unlock(&rxnet->call_lock);
  84 -               cond_resched();
  85 -               write_lock(&rxnet->call_lock);
  86         }
  87 -
  88 -       write_unlock(&rxnet->call_lock);
  89  }