Fix crash in key garbage collector when using request_key (rhbz 1272172)

0001-KEYS-Fix-crash-when-attempt-to-garbage-collect-an-un.patch

@@ -0,0 +1,78 @@
+From e2293f0c696f863c3175c199b96de3711019352f Mon Sep 17 00:00:00 2001
+From: David Howells <dhowells@redhat.com>
+Date: Thu, 15 Oct 2015 17:21:37 +0100
+Subject: [PATCH 1/2] KEYS: Fix crash when attempt to garbage collect an
+ uninstantiated keyring
+
+    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: Dmitry Vyukov <dvyukov@google.com>
+    Signed-off-by: David Howells <dhowells@redhat.com>
+---
+ security/keys/gc.c | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/security/keys/gc.c b/security/keys/gc.c
+index 39eac1fd5706..addf060399e0 100644
+--- a/security/keys/gc.c
++++ b/security/keys/gc.c
+@@ -134,8 +134,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
+ 		kdebug("- %u", key->serial);
+ 		key_check(key);
+ 
+-		/* Throw away the key data */
+-		if (key->type->destroy)
++		/* Throw away the key data if the key is instantiated */
++		if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
++		    !test_bit(KEY_FLAG_NEGATIVE, &key->flags) &&
++		    key->type->destroy)
+ 			key->type->destroy(key);
+ 
+ 		security_key_free(key);
+-- 
+2.4.3
+

0002-KEYS-Don-t-permit-request_key-to-construct-a-new-key.patch

@@ -0,0 +1,34 @@
+From 637114624bcf468a32af842a4356aab607457e62 Mon Sep 17 00:00:00 2001
+From: David Howells <dhowells@redhat.com>
+Date: Mon, 19 Oct 2015 11:33:38 +0100
+Subject: [PATCH 2/2] KEYS: Don't permit request_key() to construct a new
+ keyring
+
+    If request_key() is used to find a keyring, only do the search part - don't
+    do the construction part if the keyring was not found by the search.  We
+    don't really want keyrings in the negative instantiated state since the
+    rejected/negative instantiation error value in the payload is unioned with
+    keyring metadata.
+
+    Signed-off-by: David Howells <dhowells@redhat.com>
+---
+ security/keys/request_key.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/security/keys/request_key.c b/security/keys/request_key.c
+index 486ef6fa393b..0d6253124278 100644
+--- a/security/keys/request_key.c
++++ b/security/keys/request_key.c
+@@ -440,6 +440,9 @@ static struct key *construct_key_and_link(struct keyring_search_context *ctx,
+ 
+ 	kenter("");
+ 
++	if (ctx->index_key.type == &key_type_keyring)
++		return ERR_PTR(-EPERM);
++	
+ 	user = key_user_lookup(current_fsuid());
+ 	if (!user)
+ 		return ERR_PTR(-ENOMEM);
+-- 
+2.4.3
+

kernel.spec

@@ -587,6 +587,10 @@ Patch508: kexec-uefi-copy-secure_boot-flag-in-boot-params.patch
 #rhbz 1239050
 Patch509: ideapad-laptop-Add-Lenovo-Yoga-3-14-to-no_hw_rfkill-.patch
 
+#rhbz 1272172
+Patch510: 0001-KEYS-Fix-crash-when-attempt-to-garbage-collect-an-un.patch
+Patch511: 0002-KEYS-Don-t-permit-request_key-to-construct-a-new-key.patch
+
 Patch904: kdbus.patch
 
 # END OF PATCH DEFINITIONS
@@ -2032,6 +2036,9 @@ fi
 #
 # 
 %changelog
+* Mon Oct 19 2015 Josh Boyer <jwboyer@fedoraproject.org>
+- Fix crash in key garbage collector when using request_key (rhbz 1272172)
+
 * Fri Oct 16 2015 Laura Abbott <labbott@redhat.com> - 4.3.0-0.rc5.git2.1
 - Linux v4.3-rc5-65-g69984b6