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| author | David Howells <dhowells@redhat.com> | 2010-09-10 10:59:46 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-09-10 16:30:00 +0200 |
| commit | 9d1ac65a9698513d00e5608d93fca0c53f536c14 (patch) | |
| tree | 859809638bdf52f56b6b3890bedefcc1bae89b32 /security/keys/keyctl.c | |
| parent | Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block (diff) | |
| download | linux-9d1ac65a9698513d00e5608d93fca0c53f536c14.tar.xz linux-9d1ac65a9698513d00e5608d93fca0c53f536c14.zip | |
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>
Diffstat (limited to 'security/keys/keyctl.c')
| -rw-r--r-- | security/keys/keyctl.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index b2b0998d6abd..3868c6700b58 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; |