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Commit bfeb0360 authored by David Howells's avatar David Howells Committed by Paul E. McKenney
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KEYS: Fix an RCU warning 



Fix the following RCU warning:

===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
security/keys/request_key.c:116 invoked rcu_dereference_check() without protection!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
1 lock held by keyctl/5372:
 #0:  (key_types_sem){.+.+.+}, at: [<ffffffff811a4e3d>] key_type_lookup+0x1c/0x70

stack backtrace:
Pid: 5372, comm: keyctl Not tainted 2.6.34-rc3-cachefs #150
Call Trace:
 [<ffffffff810515f8>] lockdep_rcu_dereference+0xaa/0xb2
 [<ffffffff811a9220>] call_sbin_request_key+0x156/0x2b6
 [<ffffffff811a4c66>] ? __key_instantiate_and_link+0xb1/0xdc
 [<ffffffff811a4cd3>] ? key_instantiate_and_link+0x42/0x5f
 [<ffffffff811a96b8>] ? request_key_auth_new+0x17b/0x1f3
 [<ffffffff811a8e00>] ? request_key_and_link+0x271/0x400
 [<ffffffff810aba6f>] ? kmem_cache_alloc+0xe1/0x118
 [<ffffffff811a8f1a>] request_key_and_link+0x38b/0x400
 [<ffffffff811a7b72>] sys_request_key+0xf7/0x14a
 [<ffffffff81052227>] ? trace_hardirqs_on_caller+0x10c/0x130
 [<ffffffff81393f5c>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b

This was caused by doing:

	[root@andromeda ~]# keyctl newring fred @s
	539196288
	[root@andromeda ~]# keyctl request2 user a a 539196288
	request_key: Required key not available

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 8b46f880

security/keys/request_key.c

+8 −5
Original line number Diff line number Diff line
@@ -68,7 +68,8 @@ static int call_sbin_request_key(struct key_construction *cons, 
{

	const struct cred *cred = current_cred();

	key_serial_t prkey, sskey;

	struct key *key = cons->key, *authkey = cons->authkey, *keyring;

	struct key *key = cons->key, *authkey = cons->authkey, *keyring,

		*session;

	char *argv[9], *envp[3], uid_str[12], gid_str[12];

	char key_str[12], keyring_str[3][12];

	char desc[20];
@@ -112,10 +113,12 @@ static int call_sbin_request_key(struct key_construction *cons, 
	if (cred->tgcred->process_keyring)

		prkey = cred->tgcred->process_keyring->serial;



	if (cred->tgcred->session_keyring)

		sskey = rcu_dereference(cred->tgcred->session_keyring)->serial;

	else

		sskey = cred->user->session_keyring->serial;

	rcu_read_lock();

	session = rcu_dereference(cred->tgcred->session_keyring);

	if (!session)

		session = cred->user->session_keyring;

	sskey = session->serial;

	rcu_read_unlock();



	sprintf(keyring_str[2], "%d", sskey);