From 8bc9162cd2bf37036c486b384ac445b59b334b04 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 16 Feb 2016 23:04:41 +0100 Subject: perf/x86/amd/uncore: Plug reference leak In the error path of amd_uncore_cpu_up_prepare() the newly allocated uncore struct is freed, but the percpu pointer still references it. Set it to NULL. Signed-off-by: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1602162302170.19512@nanos Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_amd_uncore.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/cpu/perf_event_amd_uncore.c b/arch/x86/kernel/cpu/perf_event_amd_uncore.c index 49742746a6c9..8836fc9fa84b 100644 --- a/arch/x86/kernel/cpu/perf_event_amd_uncore.c +++ b/arch/x86/kernel/cpu/perf_event_amd_uncore.c @@ -323,6 +323,8 @@ static int amd_uncore_cpu_up_prepare(unsigned int cpu) return 0; fail: + if (amd_uncore_nb) + *per_cpu_ptr(amd_uncore_nb, cpu) = NULL; kfree(uncore_nb); return -ENOMEM; } -- cgit v1.2.3-58-ga151 From b4f75d44bed1bdbb14ac704bfc38f62a3675e591 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 9 Feb 2016 20:11:20 +0000 Subject: perf/core: Remove bogus UP_CANCELED hotplug state If CPU_UP_PREPARE fails the perf hotplug code calls perf_event_exit_cpu(), which is a pointless exercise. The cpu is not online, so the smp function calls return -ENXIO. So the result is a list walk to call noops. Remove it. Signed-off-by: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Link: http://lkml.kernel.org/r/20160209201007.682184765@linutronix.de Signed-off-by: Ingo Molnar --- kernel/events/core.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 5946460b2425..474ffeafe363 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9286,7 +9286,6 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) perf_event_init_cpu(cpu); break; - case CPU_UP_CANCELED: case CPU_DOWN_PREPARE: perf_event_exit_cpu(cpu); break; -- cgit v1.2.3-58-ga151 From 27ca9236c96f4a21b72a2b4f08260efeab951bd0 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 9 Feb 2016 20:11:26 +0000 Subject: perf/core: Remove the bogus and dangerous CPU_DOWN_FAILED hotplug state If CPU_DOWN_PREPARE fails the perf hotplug notifier is called for CPU_DOWN_FAILED and calls perf_event_init_cpu(), which checks whether the swhash is referenced. If yes it allocates a new hash and stores the pointer in the per cpu data structure. But at this point the cpu is still online, so there must be a valid hash already. By overwriting the pointer the existing hash is not longer accessible. Remove the CPU_DOWN_FAILED state, as there is nothing to (re)allocate. Signed-off-by: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Link: http://lkml.kernel.org/r/20160209201007.763417379@linutronix.de Signed-off-by: Ingo Molnar --- kernel/events/core.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 474ffeafe363..4aa64a85a7b7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9282,7 +9282,6 @@ perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) switch (action & ~CPU_TASKS_FROZEN) { case CPU_UP_PREPARE: - case CPU_DOWN_FAILED: perf_event_init_cpu(cpu); break; -- cgit v1.2.3-58-ga151 From 059fcd8cd16622da6513804a7a3e826d152c6c96 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 9 Feb 2016 20:11:34 +0000 Subject: perf/core: Plug potential memory leak in CPU_UP_PREPARE If CPU_UP_PREPARE is called it is not guaranteed, that a previously allocated and assigned hash has been freed already, but perf_event_init_cpu() unconditionally allocates and assignes a new hash if the swhash is referenced. By overwriting the pointer the existing hash is not longer accessible. Verify that there is no hash assigned on this cpu before allocating and assigning a new one. Signed-off-by: Thomas Gleixner Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Vince Weaver Link: http://lkml.kernel.org/r/20160209201007.843269966@linutronix.de Signed-off-by: Ingo Molnar --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 4aa64a85a7b7..0d58522103cd 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9206,7 +9206,7 @@ static void perf_event_init_cpu(int cpu) struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu); mutex_lock(&swhash->hlist_mutex); - if (swhash->hlist_refcount > 0) { + if (swhash->hlist_refcount > 0 && !swevent_hlist_deref(swhash)) { struct swevent_hlist *hlist; hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu)); -- cgit v1.2.3-58-ga151