From patchwork Fri Oct 20 07:23:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 10019043 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 D4C8B602CB for ; Fri, 20 Oct 2017 07:27:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C60F328ECD for ; Fri, 20 Oct 2017 07:27:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B98E828ECF; Fri, 20 Oct 2017 07:27:45 +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=-3.7 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, RCVD_IN_DNSWL_MED, RCVD_IN_SORBS_SPAM autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 58B4428ECD for ; Fri, 20 Oct 2017 07:27:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=rwYVjsAVkI8mm0r/FIjJyqkysiO3Zj1dIevwdIp7Qz4=; b=BwET8f6F69yHAkxba0CvpA5pqY Zm4YIjDB9cggYO9f2Dk0gKeXIH+RshCb0S0oyowTvcGBjgIkbNdjENkIIixicZBP1J+qCXEdq8YKy ++/x6DH0E5SE9OHVT+jNcVAOctmeUBTBNZ59txCaJWioOuPNrmiAwlaSygbpEMzDsQNBXUKiybVpx IQUgCfb3jQk42VfNwaSZyiROGQPVGb7PBEM7ZUTMHWASOFsYZeVPjwznEmvZH5zhVACWZliFFwb9D nSPTKf7eYjH4j2ZZssfS8XhL6AF9X0/Plze5lAI7HDc3gxXiFwK42c2F92JRcILhp9/xEOoC/3xgF zTj2atGw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1e5RiV-0000A4-HR; Fri, 20 Oct 2017 07:27:39 +0000 Received: from mga05.intel.com ([192.55.52.43]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1e5RgW-0006Eb-Sp; Fri, 20 Oct 2017 07:26:07 +0000 Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP; 20 Oct 2017 00:25:15 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,405,1503385200"; d="scan'208";a="911830989" Received: from elena-thinkpad-x230.fi.intel.com ([10.237.72.87]) by FMSMGA003.fm.intel.com with ESMTP; 20 Oct 2017 00:25:02 -0700 From: Elena Reshetova To: davem@davemloft.net Subject: [PATCH 12/15] drivers, net, ppp: convert asyncppp.refcnt from atomic_t to refcount_t Date: Fri, 20 Oct 2017 10:23:46 +0300 Message-Id: <1508484229-19706-13-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1508484229-19706-1-git-send-email-elena.reshetova@intel.com> References: <1508484229-19706-1-git-send-email-elena.reshetova@intel.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20171020_002537_457401_8EF4ACA6 X-CRM114-Status: GOOD ( 10.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peterz@infradead.org, matanb@mellanox.com, paulus@samba.org, zbr@ioremap.net, Elena Reshetova , nbd@openwrt.org, linux-rdma@vger.kernel.org, saeedm@mellanox.com, ganeshgr@chelsio.com, ajk@comnets.uni-bremen.de, keescook@chromium.org, sean.wang@mediatek.com, leonro@mellanox.com, linux-mediatek@lists.infradead.org, john@phrozen.org, matthias.bgg@gmail.com, linux-hams@vger.kernel.org, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, yishaih@mellanox.com, linux-kernel@vger.kernel.org, linux-ppp@vger.kernel.org, tariqt@mellanox.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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 asyncppp.refcnt 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 --- drivers/net/ppp/ppp_async.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c index 814fd8f..1b28e6e 100644 --- a/drivers/net/ppp/ppp_async.c +++ b/drivers/net/ppp/ppp_async.c @@ -69,7 +69,7 @@ struct asyncppp { struct tasklet_struct tsk; - atomic_t refcnt; + refcount_t refcnt; struct semaphore dead_sem; struct ppp_channel chan; /* interface to generic ppp layer */ unsigned char obuf[OBUFSIZE]; @@ -140,14 +140,14 @@ static struct asyncppp *ap_get(struct tty_struct *tty) read_lock(&disc_data_lock); ap = tty->disc_data; if (ap != NULL) - atomic_inc(&ap->refcnt); + refcount_inc(&ap->refcnt); read_unlock(&disc_data_lock); return ap; } static void ap_put(struct asyncppp *ap) { - if (atomic_dec_and_test(&ap->refcnt)) + if (refcount_dec_and_test(&ap->refcnt)) up(&ap->dead_sem); } @@ -185,7 +185,7 @@ ppp_asynctty_open(struct tty_struct *tty) skb_queue_head_init(&ap->rqueue); tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap); - atomic_set(&ap->refcnt, 1); + refcount_set(&ap->refcnt, 1); sema_init(&ap->dead_sem, 0); ap->chan.private = ap; @@ -234,7 +234,7 @@ ppp_asynctty_close(struct tty_struct *tty) * our channel ops (i.e. ppp_async_send/ioctl) are in progress * by the time it returns. */ - if (!atomic_dec_and_test(&ap->refcnt)) + if (!refcount_dec_and_test(&ap->refcnt)) down(&ap->dead_sem); tasklet_kill(&ap->tsk);