• David Howells's avatar
    keys: don't need to use RCU in keyring_read() as semaphore is held · b59ec78c
    David Howells authored
    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: [<ffffffff81177f7c>] keyctl_read_key+0x9c/0xcf
    
    stack backtrace:
    Pid: 2144, comm: keyctl Not tainted 2.6.34-rc2-cachefs #113
    Call Trace:
     [<ffffffff8105121f>] lockdep_rcu_dereference+0xaa/0xb2
     [<ffffffff811762d5>] keyring_read+0x4d/0xe7
     [<ffffffff81177f8c>] keyctl_read_key+0xac/0xcf
     [<ffffffff811788d4>] sys_keyctl+0x75/0xb9
     [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    Cc: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarJames Morris <jmorris@namei.org>
    b59ec78c
keyring.c 25.6 KB