Messages in this thread | | | Date | Wed, 21 Apr 2010 13:12:19 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] KEYS: Fix an RCU warning in the reading of user keys |
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On Wed, Apr 21, 2010 at 05:36:35PM +0100, David Howells wrote: > Fix an RCU warning in the reading of user keys: > > =================================================== > [ INFO: suspicious rcu_dereference_check() usage. ] > --------------------------------------------------- > security/keys/user_defined.c:202 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/3637: > #0: (&key->sem){+++++.}, at: [<ffffffff811a80ae>] keyctl_read_key+0x9c/0xcf > > stack backtrace: > Pid: 3637, comm: keyctl Not tainted 2.6.34-rc5-cachefs #18 > Call Trace: > [<ffffffff81051f6c>] lockdep_rcu_dereference+0xaa/0xb2 > [<ffffffff811aa55f>] user_read+0x47/0x91 > [<ffffffff811a80be>] keyctl_read_key+0xac/0xcf > [<ffffffff811a8a06>] sys_keyctl+0x75/0xb7 > [<ffffffff81001eeb>] system_call_fastpath+0x16/0x1b
Queued for 2.6.34, thank you David!
Thanx, Paul
> Signed-off-by: David Howells <dhowells@redhat.com> > --- > > security/keys/user_defined.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c > index 7c687d5..e9aa079 100644 > --- a/security/keys/user_defined.c > +++ b/security/keys/user_defined.c > @@ -199,7 +199,8 @@ long user_read(const struct key *key, char __user *buffer, size_t buflen) > struct user_key_payload *upayload; > long ret; > > - upayload = rcu_dereference(key->payload.data); > + upayload = rcu_dereference_protected( > + key->payload.data, rwsem_is_locked(&((struct key *)key)->sem)); > ret = upayload->datalen; > > /* we can return the data as is */ >
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