From: David Howells Date: Tue, 27 Apr 2010 21:05:11 +0000 (-0700) Subject: keys: don't need to use RCU in keyring_read() as semaphore is held X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b59ec78cdcc57e02bc3dddfa7134a2f0fd15c34d;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git keys: don't need to use RCU in keyring_read() as semaphore is held keyring_read() doesn't need to use rcu_dereference() to access the keyring payload as the caller holds the key semaphore to prevent modifications from happening whilst the data is read out. This should solve the following warning: =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- security/keys/keyring.c:204 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/2144: #0: (&key->sem){+++++.}, at: [] keyctl_read_key+0x9c/0xcf stack backtrace: Pid: 2144, comm: keyctl Not tainted 2.6.34-rc2-cachefs #113 Call Trace: [] lockdep_rcu_dereference+0xaa/0xb2 [] keyring_read+0x4d/0xe7 [] keyctl_read_key+0xac/0xcf [] sys_keyctl+0x75/0xb9 [] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells Cc: Herbert Xu Signed-off-by: Andrew Morton Signed-off-by: James Morris --- diff --git a/security/keys/keyring.c b/security/keys/keyring.c index e814d2109f8e..dd7cd0f8e13c 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -201,7 +201,7 @@ static long keyring_read(const struct key *keyring, int loop, ret; ret = 0; - klist = rcu_dereference(keyring->payload.subscriptions); + klist = keyring->payload.subscriptions; if (klist) { /* calculate how much data we could return */