From c50ba0cfc073d1ec5425e33a98e738f84cb0bd51 Mon Sep 17 00:00:00 2001 From: Roland Xu Date: Mon, 30 Sep 2024 17:56:56 +0800 Subject: [PATCH] rtmutex: Drop rt_mutex::wait_lock before scheduling stable inclusion from stable-v6.6.51 commit 85f03ca98e07cd0786738b56ae73740bce0ac27f category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAU9M4 CVE: CVE-2024-46829 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=85f03ca98e07cd0786738b56ae73740bce0ac27f -------------------------------- commit d33d26036a0274b472299d7dcdaa5fb34329f91b upstream. rt_mutex_handle_deadlock() is called with rt_mutex::wait_lock held. In the good case it returns with the lock held and in the deadlock case it emits a warning and goes into an endless scheduling loop with the lock held, which triggers the 'scheduling in atomic' warning. Unlock rt_mutex::wait_lock in the dead lock case before issuing the warning and dropping into the schedule for ever loop. [ tglx: Moved unlock before the WARN(), removed the pointless comment, massaged changelog, added Fixes tag ] Fixes: 3d5c9340d194 ("rtmutex: Handle deadlock detection smarter") Signed-off-by: Roland Xu Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/ME0P300MB063599BEF0743B8FA339C2CECC802@ME0P300MB0635.AUSP300.PROD.OUTLOOK.COM Signed-off-by: Greg Kroah-Hartman Signed-off-by: Xiongfeng Wang --- kernel/locking/rtmutex.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 21db0df0eb00..bf3a28ee7d8f 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1624,6 +1624,7 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock, } static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock, + struct rt_mutex_base *lock, struct rt_mutex_waiter *w) { /* @@ -1636,10 +1637,10 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock, if (build_ww_mutex() && w->ww_ctx) return; - /* - * Yell loudly and stop the task right here. - */ + raw_spin_unlock_irq(&lock->wait_lock); + WARN(1, "rtmutex deadlock detected\n"); + while (1) { set_current_state(TASK_INTERRUPTIBLE); schedule(); @@ -1693,7 +1694,7 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock, } else { __set_current_state(TASK_RUNNING); remove_waiter(lock, waiter); - rt_mutex_handle_deadlock(ret, chwalk, waiter); + rt_mutex_handle_deadlock(ret, chwalk, lock, waiter); } /* -- Gitee