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Groups > linux.kernel > #1269612

[PATCH 3.2 59/60] KEYS: Fix race between key destruction and finding a keyring by name

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3.2.73-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

commit 94c4554ba07adbdde396748ee7ae01e86cf2d8d7 upstream.

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: Petr Matousek <pmatouse@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
[carnil: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 security/keys/gc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -172,6 +172,10 @@ static noinline void key_gc_unused_key(s
 {
 	key_check(key);
 
+	/* Throw away the key data */
+	if (key->type->destroy)
+		key->type->destroy(key);
+
 	security_key_free(key);
 
 	/* deal with the user's key tracking and quota */
@@ -186,10 +190,6 @@ static noinline void key_gc_unused_key(s
 	if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
 		atomic_dec(&key->user->nikeys);
 
-	/* now throw away the key memory */
-	if (key->type->destroy)
-		key->type->destroy(key);
-
 	key_user_put(key->user);
 
 	kfree(key->description);

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[PATCH 3.2 00/60] 3.2.73-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 43/60] dm btree remove: fix a bug when rebalancing  nodes after removal Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 27/60] 3w-9xxx: don't unmap bounce buffered commands Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 12/60] genirq: Fix race in register_irq_proc() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 31/60] iommu/vt-d: fix range computation when making  room for large pages Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 28/60] xen-blkfront: check for null drvdata in  blkback_changed (XenbusStateClosing) Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 32/60] xhci: don't finish a TD if we get a short  transfer event mid TD Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 46/60] md/raid1: don't clear bitmap bit when  bad-block-list write fails. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 24/60] iwlwifi: dvm: fix D3 firmware PN programming Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 04/60] regmap: debugfs: Don't bother actually printing  when calculating max length Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 55/60] asix: Don't reset PHY on if_up for ASIX 88772 Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 08/60] UBI: Validate data_size Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 53/60] skbuff: Fix skb checksum partial check. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 38/60] IB/cm: Fix rb-tree duplicate free and  use-after-free Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 20/60] usb: Add device quirk for Logitech PTZ cameras Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 33/60] xhci: handle no ping response error properly Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 19/60] USB: Add reset-resume quirk for two Plantronics  usb headphones. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 44/60] dm btree: fix leak of bufio-backed block in  btree_split_beneath error path Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 40/60] powerpc/rtas: Validate rtas.entry before  calling enter_rtas() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 34/60] xhci: Switch Intel Lynx Point LP ports to EHCI  on shutdown. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 07/60] x86/xen: Do not clip xen_e820_map to  xen_e820_map_entries when sanitizing map Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 03/60] regmap: debugfs: Ensure we don't underflow when  printing access masks Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 51/60] net: add length argument to  skb_copy_and_csum_datagram_iovec Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 05/60] ath9k: declare required extra tx headroom Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 39/60] drm/nouveau/gem: return only valid domain when  there's only one Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 06/60] m68k: Define asmlinkage_protect Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 26/60] sched/core: Fix TASK_DEAD race in  finish_task_switch() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 45/60] md/raid1: ensure device failure recorded before  write request returns. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 15/60] md/raid0: update queue parameter in a safer  location. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 59/60] KEYS: Fix race between key destruction and  finding a keyring by name Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 23/60] ppp: don't override sk->sk_state in  pppoe_flush_dev() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 49/60] mvsas: Fix NULL pointer dereference in  mvs_slot_task_free Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 58/60] KVM: x86: work around infinite loop in  microcode when #AC is delivered Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 42/60] ppp: fix pppoe_dev deletion condition in  pppoe_release() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 10/60] MIPS: dma-default: Fix 32-bit fall back to GFP_DMA Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 50/60] sched: declare pid_alive as inline Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 17/60] clocksource: Fix abs() usage w/ 64bit values Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 36/60] crypto: api - Only abort operations on fatal signal Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 16/60] md/raid0: apply base queue limits *before*  disk_stack_limits Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 47/60] md/raid10: ensure device failure recorded  before write request returns. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 57/60] Failing to send a CLOSE if file is opened  WRONLY and server reboots on a 4.x mount Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 14/60] [SMB3] Do not fall back to SMBWriteX in  set_file_size error cases Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  Re: [PATCH 3.2 00/60] 3.2.73-rc1 review Guenter Roeck <linux@roeck-us.net> - 2015-11-15 14:50 +0100
    Re: [PATCH 3.2 00/60] 3.2.73-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2015-11-16 12:20 +0100

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