The following commit has been merged into the timers/urgent branch of tip:
Commit-ID: 73d20564e0dcae003e0d79977f044d5e57496304
Gitweb: https://git.kernel.org/tip/73d20564e0dcae003e0d79977f044d5e57496304
Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate: Tue, 31 Mar 2020 22:18:49 +02:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Wed, 01 Apr 2020 13:20:14 +02:00
hrtimer: Don't dereference the hrtimer pointer after the callback
A hrtimer can be released in its callback, but lockdep_hrtimer_exit()
dereferences the pointer after the callback returns, i.e. a potential use
after free.
Retrieve the context in which the hrtimer expires before the callback is
invoked and use it in lockdep_hrtimer_exit().
Fixes: 40db173965c0 ("lockdep: Add hrtimer context tracing bits")
Reported-by: syzbot+62c155c276e580cfb606@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200331201849.fkp2siy3vcdqvqlz@xxxxxxxxxxxxx
---
include/linux/irqflags.h | 27 ++++++++++++++++-----------
kernel/time/hrtimer.c | 5 +++--
2 files changed, 19 insertions(+), 13 deletions(-)
diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
index ceca42d..61a9ced 100644
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -58,16 +58,21 @@ do { \
} while (0)
# define lockdep_hrtimer_enter(__hrtimer) \
- do { \
- if (!__hrtimer->is_hard) \
- current->irq_config = 1; \
- } while (0)
-
-# define lockdep_hrtimer_exit(__hrtimer) \
- do { \
- if (!__hrtimer->is_hard) \
+({ \
+ bool __expires_hardirq = true; \
+ \
+ if (!__hrtimer->is_hard) { \
+ current->irq_config = 1; \
+ __expires_hardirq = false; \
+ } \
+ __expires_hardirq; \
+})
+
+# define lockdep_hrtimer_exit(__expires_hardirq) \
+ do { \
+ if (!__expires_hardirq) \
current->irq_config = 0; \
- } while (0)
+ } while (0)
# define lockdep_posixtimer_enter() \
do { \
@@ -102,8 +107,8 @@ do { \
# define lockdep_hardirq_exit() do { } while (0)
# define lockdep_softirq_enter() do { } while (0)
# define lockdep_softirq_exit() do { } while (0)
-# define lockdep_hrtimer_enter(__hrtimer) do { } while (0)
-# define lockdep_hrtimer_exit(__hrtimer) do { } while (0)
+# define lockdep_hrtimer_enter(__hrtimer) false
+# define lockdep_hrtimer_exit(__context) do { } while (0)
# define lockdep_posixtimer_enter() do { } while (0)
# define lockdep_posixtimer_exit() do { } while (0)
# define lockdep_irq_work_enter(__work) do { } while (0)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index d0a5ba3..d89da1c 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1480,6 +1480,7 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
unsigned long flags) __must_hold(&cpu_base->lock)
{
enum hrtimer_restart (*fn)(struct hrtimer *);
+ bool expires_in_hardirq;
int restart;
lockdep_assert_held(&cpu_base->lock);
@@ -1514,11 +1515,11 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
*/
raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
trace_hrtimer_expire_entry(timer, now);
- lockdep_hrtimer_enter(timer);
+ expires_in_hardirq = lockdep_hrtimer_enter(timer);
restart = fn(timer);
- lockdep_hrtimer_exit(timer);
+ lockdep_hrtimer_exit(expires_in_hardirq);
trace_hrtimer_expire_exit(timer);
raw_spin_lock_irq(&cpu_base->lock);
|