From patchwork Fri Oct 20 12:15:51 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 10020121 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 20C1660211 for ; Fri, 20 Oct 2017 12:19:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2339C2854A for ; Fri, 20 Oct 2017 12:19:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 165EF28E6F; Fri, 20 Oct 2017 12:19:38 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5F4B528E6D for ; Fri, 20 Oct 2017 12:19:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753332AbdJTMQt (ORCPT ); Fri, 20 Oct 2017 08:16:49 -0400 Received: from mga11.intel.com ([192.55.52.93]:61218 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752790AbdJTMQr (ORCPT ); Fri, 20 Oct 2017 08:16:47 -0400 Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Oct 2017 05:16:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,405,1503385200"; d="scan'208";a="911899022" Received: from elena-thinkpad-x230.fi.intel.com ([10.237.72.87]) by FMSMGA003.fm.intel.com with ESMTP; 20 Oct 2017 05:16:40 -0700 From: Elena Reshetova To: mingo@redhat.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, tj@kernel.org, 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, linux-mm@kvack.org, axboe@kernel.dk, Elena Reshetova Subject: [PATCH 09/15] perf/ring_buffer: convert ring_buffer.aux_refcount to refcount_t Date: Fri, 20 Oct 2017 15:15:51 +0300 Message-Id: <1508501757-15784-10-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1508501757-15784-1-git-send-email-elena.reshetova@intel.com> References: <1508501757-15784-1-git-send-email-elena.reshetova@intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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.aux_refcount is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova --- kernel/events/core.c | 2 +- kernel/events/internal.h | 2 +- kernel/events/ring_buffer.c | 6 +++--- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 66d7e18..3848480 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5182,7 +5182,7 @@ static void perf_mmap_close(struct vm_area_struct *vma) /* this has to be the last one */ rb_free_aux(rb); - WARN_ON_ONCE(atomic_read(&rb->aux_refcount)); + WARN_ON_ONCE(refcount_read(&rb->aux_refcount)); mutex_unlock(&event->mmap_mutex); } diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 1cdd9fa..cc5b545 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -48,7 +48,7 @@ struct ring_buffer { atomic_t aux_mmap_count; unsigned long aux_mmap_locked; void (*free_aux)(void *); - atomic_t aux_refcount; + refcount_t aux_refcount; void **aux_pages; void *aux_priv; diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 86e1379..08838cd6 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -357,7 +357,7 @@ void *perf_aux_output_begin(struct perf_output_handle *handle, if (!atomic_read(&rb->aux_mmap_count)) goto err; - if (!atomic_inc_not_zero(&rb->aux_refcount)) + if (!refcount_inc_not_zero(&rb->aux_refcount)) goto err; /* @@ -655,7 +655,7 @@ int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, * we keep a refcount here to make sure either of the two can * reference them safely. */ - atomic_set(&rb->aux_refcount, 1); + refcount_set(&rb->aux_refcount, 1); rb->aux_overwrite = overwrite; rb->aux_watermark = watermark; @@ -674,7 +674,7 @@ int rb_alloc_aux(struct ring_buffer *rb, struct perf_event *event, void rb_free_aux(struct ring_buffer *rb) { - if (atomic_dec_and_test(&rb->aux_refcount)) + if (refcount_dec_and_test(&rb->aux_refcount)) __rb_free_aux(rb); }