tegrakernel/kernel/kernel-4.9/rt-patches/0026-futex-Avoid-freeing-an...

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From 25bd9473c12614a8c6600755b477fbf9dd9f57da Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 10 Apr 2017 18:03:36 +0200
Subject: [PATCH 026/365] futex: Avoid freeing an active timer
Upstream commit 97181f9bd57405b879403763284537e27d46963d
Alexander reported a hrtimer debug_object splat:
ODEBUG: free active (active state 0) object type: hrtimer hint: hrtimer_wakeup (kernel/time/hrtimer.c:1423)
debug_object_free (lib/debugobjects.c:603)
destroy_hrtimer_on_stack (kernel/time/hrtimer.c:427)
futex_lock_pi (kernel/futex.c:2740)
do_futex (kernel/futex.c:3399)
SyS_futex (kernel/futex.c:3447 kernel/futex.c:3415)
do_syscall_64 (arch/x86/entry/common.c:284)
entry_SYSCALL64_slow_path (arch/x86/entry/entry_64.S:249)
Which was caused by commit:
cfafcd117da0 ("futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()")
... losing the hrtimer_cancel() in the shuffle. Where previously the
hrtimer_cancel() was done by rt_mutex_slowlock() we now need to do it
manually.
Reported-by: Alexander Levin <alexander.levin@verizon.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: cfafcd117da0 ("futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()")
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1704101802370.2906@nanos
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/futex.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index 963bc8e5f3a9..551b647f6167 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2802,8 +2802,10 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
out_put_key:
put_futex_key(&q.key);
out:
- if (to)
+ if (to) {
+ hrtimer_cancel(&to->timer);
destroy_hrtimer_on_stack(&to->timer);
+ }
return ret != -EINTR ? ret : -ERESTARTNOINTR;
uaddr_faulted:
--
2.28.0