1. 19 Nov, 2015 2 commits
    • David Howells's avatar
      KEYS: Fix crash when attempt to garbage collect an uninstantiated keyring · 16d8da6c
      David Howells authored
      [ Upstream commit f05819df ]
      
      The following sequence of commands:
      
          i=`keyctl add user a a @s`
          keyctl request2 keyring foo bar @t
          keyctl unlink $i @s
      
      tries to invoke an upcall to instantiate a keyring if one doesn't already
      exist by that name within the user's keyring set.  However, if the upcall
      fails, the code sets keyring->type_data.reject_error to -ENOKEY or some
      other error code.  When the key is garbage collected, the key destroy
      function is called unconditionally and keyring_destroy() uses list_empty()
      on keyring->type_data.link - which is in a union with reject_error.
      Subsequently, the kernel tries to unlink the keyring from the keyring names
      list - which oopses like this:
      
      	BUG: unable to handle kernel paging request at 00000000ffffff8a
      	IP: [<ffffffff8126e051>] keyring_destroy+0x3d/0x88
      	...
      	Workqueue: events key_garbage_collector
      	...
      	RIP: 0010:[<ffffffff8126e051>] keyring_destroy+0x3d/0x88
      	RSP: 0018:ffff88003e2f3d30  EFLAGS: 00010203
      	RAX: 00000000ffffff82 RBX: ffff88003bf1a900 RCX: 0000000000000000
      	RDX: 0000000000000000 RSI: 000000003bfc6901 RDI: ffffffff81a73a40
      	RBP: ffff88003e2f3d38 R08: 0000000000000152 R09: 0000000000000000
      	R10: ffff88003e2f3c18 R11: 000000000000865b R12: ffff88003bf1a900
      	R13: 0000000000000000 R14: ffff88003bf1a908 R15: ffff88003e2f4000
      	...
      	CR2: 00000000ffffff8a CR3: 000000003e3ec000 CR4: 00000000000006f0
      	...
      	Call Trace:
      	 [<ffffffff8126c756>] key_gc_unused_keys.constprop.1+0x5d/0x10f
      	 [<ffffffff8126ca71>] key_garbage_collector+0x1fa/0x351
      	 [<ffffffff8105ec9b>] process_one_work+0x28e/0x547
      	 [<ffffffff8105fd17>] worker_thread+0x26e/0x361
      	 [<ffffffff8105faa9>] ? rescuer_thread+0x2a8/0x2a8
      	 [<ffffffff810648ad>] kthread+0xf3/0xfb
      	 [<ffffffff810647ba>] ? kthread_create_on_node+0x1c2/0x1c2
      	 [<ffffffff815f2ccf>] ret_from_fork+0x3f/0x70
      	 [<ffffffff810647ba>] ? kthread_create_on_node+0x1c2/0x1c2
      
      Note the value in RAX.  This is a 32-bit representation of -ENOKEY.
      
      The solution is to only call ->destroy() if the key was successfully
      instantiated.
      Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Tested-by: default avatarDmitry Vyukov <dvyukov@google.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      16d8da6c
    • David Howells's avatar
      KEYS: Fix race between key destruction and finding a keyring by name · 1ee2c9bd
      David Howells authored
      [ Upstream commit 94c4554b ]
      
      There appears to be a race between:
      
       (1) key_gc_unused_keys() which frees key->security and then calls
           keyring_destroy() to unlink the name from the name list
      
       (2) find_keyring_by_name() which calls key_permission(), thus accessing
           key->security, on a key before checking to see whether the key usage is 0
           (ie. the key is dead and might be cleaned up).
      
      Fix this by calling ->destroy() before cleaning up the core key data -
      including key->security.
      Reported-by: default avatarPetr Matousek <pmatouse@redhat.com>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
      1ee2c9bd
  2. 15 Nov, 2015 36 commits
  3. 13 Nov, 2015 2 commits