From: Elena Reshetova <elena.reshetova@intel.com>
To: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, peterz@infradead.org,
gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk,
tj@kernel.org, mingo@redhat.com, hannes@cmpxchg.org,
lizefan@huawei.com, acme@kernel.org,
alexander.shishkin@linux.intel.com, eparis@redhat.com,
akpm@linux-foundation.org, arnd@arndb.de, luto@kernel.org,
keescook@chromium.org, tglx@linutronix.de, dvhart@infradead.org,
ebiederm@xmission.com,
Elena Reshetova <elena.reshetova@intel.com>
Subject: [PATCH 08/15] perf/ring_buffer: convert ring_buffer.refcount to refcount_t
Date: Tue, 18 Jul 2017 13:30:01 +0300 [thread overview]
Message-ID: <1500373808-8089-9-git-send-email-elena.reshetova@intel.com> (raw)
In-Reply-To: <1500373808-8089-1-git-send-email-elena.reshetova@intel.com>
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable ring_buffer.refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
---
kernel/events/core.c | 4 ++--
kernel/events/internal.h | 3 ++-
kernel/events/ring_buffer.c | 2 +-
3 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index faf9925..9147397 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5049,7 +5049,7 @@ struct ring_buffer *ring_buffer_get(struct perf_event *event)
rcu_read_lock();
rb = rcu_dereference(event->rb);
if (rb) {
- if (!atomic_inc_not_zero(&rb->refcount))
+ if (!refcount_inc_not_zero(&rb->refcount))
rb = NULL;
}
rcu_read_unlock();
@@ -5059,7 +5059,7 @@ struct ring_buffer *ring_buffer_get(struct perf_event *event)
void ring_buffer_put(struct ring_buffer *rb)
{
- if (!atomic_dec_and_test(&rb->refcount))
+ if (!refcount_dec_and_test(&rb->refcount))
return;
WARN_ON_ONCE(!list_empty(&rb->event_list));
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 486fd78..b8e6fdf 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -3,13 +3,14 @@
#include <linux/hardirq.h>
#include <linux/uaccess.h>
+#include <linux/refcount.h>
/* Buffer handling */
#define RING_BUFFER_WRITABLE 0x01
struct ring_buffer {
- atomic_t refcount;
+ refcount_t refcount;
struct rcu_head rcu_head;
#ifdef CONFIG_PERF_USE_VMALLOC
struct work_struct work;
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index ee97196..3353572 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -284,7 +284,7 @@ ring_buffer_init(struct ring_buffer *rb, long watermark, int flags)
else
rb->overwrite = 1;
- atomic_set(&rb->refcount, 1);
+ refcount_set(&rb->refcount, 1);
INIT_LIST_HEAD(&rb->event_list);
spin_lock_init(&rb->event_lock);
--
2.7.4
next prev parent reply other threads:[~2017-07-18 10:37 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 10:29 [PATCH 00/15] v4 kernel core pieces refcount conversions Elena Reshetova
2017-07-18 10:29 ` [PATCH 01/15] sched: convert sighand_struct.count to refcount_t Elena Reshetova
2017-07-18 10:29 ` [PATCH 02/15] sched: convert signal_struct.sigcnt " Elena Reshetova
2017-07-18 10:29 ` [PATCH 03/15] sched: convert user_struct.__count " Elena Reshetova
2017-07-18 10:29 ` [PATCH 04/15] sched: convert numa_group.refcount " Elena Reshetova
2017-07-18 10:29 ` [PATCH 05/15] sched/task_struct: convert task_struct.usage " Elena Reshetova
2017-07-18 10:29 ` [PATCH 06/15] sched/task_struct: convert task_struct.stack_refcount " Elena Reshetova
2017-07-18 10:30 ` [PATCH 07/15] perf: convert perf_event_context.refcount " Elena Reshetova
2017-07-18 10:30 ` Elena Reshetova [this message]
2017-07-18 10:30 ` [PATCH 09/15] perf/ring_buffer: convert ring_buffer.aux_refcount " Elena Reshetova
2017-07-18 10:30 ` [PATCH 10/15] uprobes: convert uprobe.ref " Elena Reshetova
2017-07-18 10:30 ` [PATCH 11/15] nsproxy: convert nsproxy.count " Elena Reshetova
2017-07-18 10:30 ` [PATCH 12/15] groups: convert group_info.usage " Elena Reshetova
2017-07-18 10:30 ` [PATCH 13/15] creds: convert cred.usage " Elena Reshetova
2017-07-18 10:30 ` [PATCH 14/15] futex: convert futex_pi_state.refcount " Elena Reshetova
2017-07-18 10:30 ` [PATCH 15/15] kcov: convert kcov.refcount " Elena Reshetova
2017-08-25 9:41 [PATCH 00/15] v4 kernel core pieces refcount conversions Elena Reshetova
2017-08-25 9:41 ` [PATCH 08/15] perf/ring_buffer: convert ring_buffer.refcount to refcount_t Elena Reshetova
2017-08-30 12:22 [PATCH 00/15] v5 kernel core pieces refcount conversions Elena Reshetova
2017-08-30 12:22 ` [PATCH 08/15] perf/ring_buffer: convert ring_buffer.refcount to refcount_t Elena Reshetova
2017-10-20 12:15 [PATCH 00/15] v5 kernel core pieces refcount conversions Elena Reshetova
2017-10-20 12:15 ` [PATCH 08/15] perf/ring_buffer: convert ring_buffer.refcount to refcount_t Elena Reshetova
2017-10-20 12:15 ` Elena Reshetova
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