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authorDavid Howells <dhowells@redhat.com>2010-09-10 09:59:46 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2010-09-10 07:30:00 -0700
commit9d1ac65a9698513d00e5608d93fca0c53f536c14 (patch)
tree859809638bdf52f56b6b3890bedefcc1bae89b32
parentff3cb3fec3c5bbb5110e652bbdd410bc99a47e9f (diff)
downloadlinux-linaro-9d1ac65a9698513d00e5608d93fca0c53f536c14.tar.gz
KEYS: Fix RCU no-lock warning in keyctl_session_to_parent()
There's an protected access to the parent process's credentials in the middle of keyctl_session_to_parent(). This results in the following RCU warning: =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- security/keys/keyctl.c:1291 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-session-/2137: #0: (tasklist_lock){.+.+..}, at: [<ffffffff811ae2ec>] keyctl_session_to_parent+0x60/0x236 stack backtrace: Pid: 2137, comm: keyctl-session- Not tainted 2.6.36-rc2-cachefs+ #1 Call Trace: [<ffffffff8105606a>] lockdep_rcu_dereference+0xaa/0xb3 [<ffffffff811ae379>] keyctl_session_to_parent+0xed/0x236 [<ffffffff811af77e>] sys_keyctl+0xb4/0xb6 [<ffffffff81001eab>] system_call_fastpath+0x16/0x1b The code should take the RCU read lock to make sure the parents credentials don't go away, even though it's holding a spinlock and has IRQ disabled. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--security/keys/keyctl.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index b2b0998d6ab..3868c6700b5 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1272,6 +1272,7 @@ long keyctl_session_to_parent(void)
keyring_r = NULL;
me = current;
+ rcu_read_lock();
write_lock_irq(&tasklist_lock);
parent = me->real_parent;
@@ -1319,6 +1320,7 @@ long keyctl_session_to_parent(void)
set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME);
write_unlock_irq(&tasklist_lock);
+ rcu_read_unlock();
if (oldcred)
put_cred(oldcred);
return 0;
@@ -1327,6 +1329,7 @@ already_same:
ret = 0;
not_permitted:
write_unlock_irq(&tasklist_lock);
+ rcu_read_unlock();
put_cred(cred);
return ret;