1. 05 Oct, 2014 38 commits
  2. 17 Sep, 2014 2 commits
    • Greg Kroah-Hartman's avatar
      Linux 3.16.3 · c13c2820
      Greg Kroah-Hartman authored
      c13c2820
    • David Howells's avatar
      KEYS: Fix termination condition in assoc array garbage collection · a4b9e45f
      David Howells authored
      commit 95389b08 upstream.
      
      This fixes CVE-2014-3631.
      
      It is possible for an associative array to end up with a shortcut node at the
      root of the tree if there are more than fan-out leaves in the tree, but they
      all crowd into the same slot in the lowest level (ie. they all have the same
      first nibble of their index keys).
      
      When assoc_array_gc() returns back up the tree after scanning some leaves, it
      can fall off of the root and crash because it assumes that the back pointer
      from a shortcut (after label ascend_old_tree) must point to a normal node -
      which isn't true of a shortcut node at the root.
      
      Should we find we're ascending rootwards over a shortcut, we should check to
      see if the backpointer is zero - and if it is, we have completed the scan.
      
      This particular bug cannot occur if the root node is not a shortcut - ie. if
      you have fewer than 17 keys in a keyring or if you have at least two keys that
      sit into separate slots (eg. a keyring and a non keyring).
      
      This can be reproduced by:
      
      	ring=`keyctl newring bar @s`
      	for ((i=1; i<=18; i++)); do last_key=`keyctl newring foo$i $ring`; done
      	keyctl timeout $last_key 2
      
      Doing this:
      
      	echo 3 >/proc/sys/kernel/keys/gc_delay
      
      first will speed things up.
      
      If we do fall off of the top of the tree, we get the following oops:
      
      BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
      IP: [<ffffffff8136cea7>] assoc_array_gc+0x2f7/0x540
      PGD dae15067 PUD cfc24067 PMD 0
      Oops: 0000 [#1] SMP
      Modules linked in: xt_nat xt_mark nf_conntrack_netbios_ns nf_conntrack_broadcast ip6t_rpfilter ip6t_REJECT xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_ni
      CPU: 0 PID: 26011 Comm: kworker/0:1 Not tainted 3.14.9-200.fc20.x86_64 #1
      Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
      Workqueue: events key_garbage_collector
      task: ffff8800918bd580 ti: ffff8800aac14000 task.ti: ffff8800aac14000
      RIP: 0010:[<ffffffff8136cea7>] [<ffffffff8136cea7>] assoc_array_gc+0x2f7/0x540
      RSP: 0018:ffff8800aac15d40  EFLAGS: 00010206
      RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8800aaecacc0
      RDX: ffff8800daecf440 RSI: 0000000000000001 RDI: ffff8800aadc2bc0
      RBP: ffff8800aac15da8 R08: 0000000000000001 R09: 0000000000000003
      R10: ffffffff8136ccc7 R11: 0000000000000000 R12: 0000000000000000
      R13: 0000000000000000 R14: 0000000000000070 R15: 0000000000000001
      FS:  0000000000000000(0000) GS:ffff88011fc00000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
      CR2: 0000000000000018 CR3: 00000000db10d000 CR4: 00000000000006f0
      Stack:
       ffff8800aac15d50 0000000000000011 ffff8800aac15db8 ffffffff812e2a70
       ffff880091a00600 0000000000000000 ffff8800aadc2bc3 00000000cd42c987
       ffff88003702df20 ffff88003702dfa0 0000000053b65c09 ffff8800aac15fd8
      Call Trace:
       [<ffffffff812e2a70>] ? keyring_detect_cycle_iterator+0x30/0x30
       [<ffffffff812e3e75>] keyring_gc+0x75/0x80
       [<ffffffff812e1424>] key_garbage_collector+0x154/0x3c0
       [<ffffffff810a67b6>] process_one_work+0x176/0x430
       [<ffffffff810a744b>] worker_thread+0x11b/0x3a0
       [<ffffffff810a7330>] ? rescuer_thread+0x3b0/0x3b0
       [<ffffffff810ae1a8>] kthread+0xd8/0xf0
       [<ffffffff810ae0d0>] ? insert_kthread_work+0x40/0x40
       [<ffffffff816ffb7c>] ret_from_fork+0x7c/0xb0
       [<ffffffff810ae0d0>] ? insert_kthread_work+0x40/0x40
      Code: 08 4c 8b 22 0f 84 bf 00 00 00 41 83 c7 01 49 83 e4 fc 41 83 ff 0f 4c 89 65 c0 0f 8f 5a fe ff ff 48 8b 45 c0 4d 63 cf 49 83 c1 02 <4e> 8b 34 c8 4d 85 f6 0f 84 be 00 00 00 41 f6 c6 01 0f 84 92
      RIP  [<ffffffff8136cea7>] assoc_array_gc+0x2f7/0x540
       RSP <ffff8800aac15d40>
      CR2: 0000000000000018
      ---[ end trace 1129028a088c0cbd ]---
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Acked-by: default avatarDon Zickus <dzickus@redhat.com>
      Signed-off-by: default avatarJames Morris <james.l.morris@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a4b9e45f