From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752767AbdCFPXI (ORCPT ); Mon, 6 Mar 2017 10:23:08 -0500 Received: from mga04.intel.com ([192.55.52.120]:52309 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753887AbdCFPWP (ORCPT ); Mon, 6 Mar 2017 10:22:15 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,254,1484035200"; d="scan'208";a="72745861" From: Elena Reshetova To: gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-bcache@vger.kernel.org, linux-raid@vger.kernel.org, linux-media@vger.kernel.org, devel@linuxdriverproject.org, linux-pci@vger.kernel.org, linux-s390@vger.kernel.org, fcoe-devel@open-fcoe.org, linux-scsi@vger.kernel.org, open-iscsi@googlegroups.com, devel@driverdev.osuosl.org, target-devel@vger.kernel.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, peterz@infradead.org, Elena Reshetova , Hans Liljestrand , Kees Cook , David Windsor Subject: [PATCH 03/29] drivers, char: convert vma_data.refcnt from atomic_t to refcount_t Date: Mon, 6 Mar 2017 16:20:50 +0200 Message-Id: <1488810076-3754-4-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> References: <1488810076-3754-1-git-send-email-elena.reshetova@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor --- drivers/char/mspec.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c index a9c2fa3..7b75669 100644 --- a/drivers/char/mspec.c +++ b/drivers/char/mspec.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -89,7 +90,7 @@ static int is_sn2; * protect in fork case where multiple tasks share the vma_data. */ struct vma_data { - atomic_t refcnt; /* Number of vmas sharing the data. */ + refcount_t refcnt; /* Number of vmas sharing the data. */ spinlock_t lock; /* Serialize access to this structure. */ int count; /* Number of pages allocated. */ enum mspec_page_type type; /* Type of pages allocated. */ @@ -144,7 +145,7 @@ mspec_open(struct vm_area_struct *vma) struct vma_data *vdata; vdata = vma->vm_private_data; - atomic_inc(&vdata->refcnt); + refcount_inc(&vdata->refcnt); } /* @@ -162,7 +163,7 @@ mspec_close(struct vm_area_struct *vma) vdata = vma->vm_private_data; - if (!atomic_dec_and_test(&vdata->refcnt)) + if (!refcount_dec_and_test(&vdata->refcnt)) return; last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT; @@ -274,7 +275,7 @@ mspec_mmap(struct file *file, struct vm_area_struct *vma, vdata->vm_end = vma->vm_end; vdata->type = type; spin_lock_init(&vdata->lock); - atomic_set(&vdata->refcnt, 1); + refcount_set(&vdata->refcnt, 1); vma->vm_private_data = vdata; vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; -- 2.7.4