| From 66339c31bc3978d5fff9c4b4cb590a861def4db2 Mon Sep 17 00:00:00 2001 |
| From: Kirill Tkhai <ktkhai@parallels.com> |
| Date: Mon, 22 Sep 2014 22:36:24 +0400 |
| Subject: sched: Use dl_bw_of() under RCU read lock |
| |
| From: Kirill Tkhai <ktkhai@parallels.com> |
| |
| commit 66339c31bc3978d5fff9c4b4cb590a861def4db2 upstream. |
| |
| dl_bw_of() dereferences rq->rd which has to have RCU read lock held. |
| Probability of use-after-free isn't zero here. |
| |
| Also add lockdep assert into dl_bw_cpus(). |
| |
| Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Link: http://lkml.kernel.org/r/20140922183624.11015.71558.stgit@localhost |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/sched/core.c | 10 ++++++++++ |
| 1 file changed, 10 insertions(+) |
| |
| --- a/kernel/sched/core.c |
| +++ b/kernel/sched/core.c |
| @@ -1977,6 +1977,8 @@ unsigned long to_ratio(u64 period, u64 r |
| #ifdef CONFIG_SMP |
| inline struct dl_bw *dl_bw_of(int i) |
| { |
| + rcu_lockdep_assert(rcu_read_lock_sched_held(), |
| + "sched RCU must be held"); |
| return &cpu_rq(i)->rd->dl_bw; |
| } |
| |
| @@ -1985,6 +1987,8 @@ static inline int dl_bw_cpus(int i) |
| struct root_domain *rd = cpu_rq(i)->rd; |
| int cpus = 0; |
| |
| + rcu_lockdep_assert(rcu_read_lock_sched_held(), |
| + "sched RCU must be held"); |
| for_each_cpu_and(i, rd->span, cpu_active_mask) |
| cpus++; |
| |
| @@ -7580,6 +7584,8 @@ static int sched_dl_global_constraints(v |
| int cpu, ret = 0; |
| unsigned long flags; |
| |
| + rcu_read_lock(); |
| + |
| /* |
| * Here we want to check the bandwidth not being set to some |
| * value smaller than the currently allocated bandwidth in |
| @@ -7601,6 +7607,8 @@ static int sched_dl_global_constraints(v |
| break; |
| } |
| |
| + rcu_read_unlock(); |
| + |
| return ret; |
| } |
| |
| @@ -7616,6 +7624,7 @@ static void sched_dl_do_global(void) |
| if (global_rt_runtime() != RUNTIME_INF) |
| new_bw = to_ratio(global_rt_period(), global_rt_runtime()); |
| |
| + rcu_read_lock(); |
| /* |
| * FIXME: As above... |
| */ |
| @@ -7626,6 +7635,7 @@ static void sched_dl_do_global(void) |
| dl_b->bw = new_bw; |
| raw_spin_unlock_irqrestore(&dl_b->lock, flags); |
| } |
| + rcu_read_unlock(); |
| } |
| |
| static int sched_rt_global_validate(void) |