Messages in this thread Patch in this message | | | From | David Howells <> | Subject | [PATCH] KEYS: Fix an RCU warning in the reading of user keys | Date | Wed, 21 Apr 2010 17:36:35 +0100 |
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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
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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