From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,LOTS_OF_MONEY,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E7CCC433E0 for ; Tue, 9 Jun 2020 00:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 173AE2072F for ; Tue, 9 Jun 2020 00:30:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591662624; bh=RyU8bCmCzVxSV2P47dF/Ddb+fy18hma9gz8vKz6FU4k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cGrtuGL9HcnGKSuKM6kazSm7d42UQfzH2M7hTnc3hNfGQvTxfp4n7N+XhfnP0/4Hn OGTisAK1157BkHS6G4Ume9a1HN2S5yCh1bxsRIzqhy5UKi8gDPL7BtwIbWdb1huFRG of//h0YGczNWZHvGKnUxpPivZ96PafJFG9ruqnuw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730796AbgFIAaW (ORCPT ); Mon, 8 Jun 2020 20:30:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:37070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730119AbgFHXPz (ORCPT ); Mon, 8 Jun 2020 19:15:55 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id ACE242076A; Mon, 8 Jun 2020 23:15:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658154; bh=RyU8bCmCzVxSV2P47dF/Ddb+fy18hma9gz8vKz6FU4k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i9/1dbXIPdp39E9OwOyyPDCNsWx1RMQtvSu4w8JY168NaNjgKA7aGG3jocoAtfWyI BI12xEQxIl+fdlB13lw2LzoNUV9qwQRDMcRINzhHaD9iW31bse4zkdzp5eD9jnvDES ax7s4S5MTgb3aJWWj4BtGdTquH+0RtmvgX7BYP5s= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: David Hildenbrand , Andrew Morton , Dan Williams , Vishal Verma , Dave Jiang , Pavel Tatashin , Linus Torvalds , Greg Kroah-Hartman , linux-nvdimm@lists.01.org Subject: [PATCH AUTOSEL 5.6 186/606] device-dax: don't leak kernel memory to user space after unloading kmem Date: Mon, 8 Jun 2020 19:05:11 -0400 Message-Id: <20200608231211.3363633-186-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org> References: <20200608231211.3363633-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Hildenbrand commit 60858c00e5f018eda711a3aa84cf62214ef62d61 upstream. Assume we have kmem configured and loaded: [root@localhost ~]# cat /proc/iomem ... 140000000-33fffffff : Persistent Memory$ 140000000-1481fffff : namespace0.0 150000000-33fffffff : dax0.0 150000000-33fffffff : System RAM Assume we try to unload kmem. This force-unloading will work, even if memory cannot get removed from the system. [root@localhost ~]# rmmod kmem [ 86.380228] removing memory fails, because memory [0x0000000150000000-0x0000000157ffffff] is onlined ... [ 86.431225] kmem dax0.0: DAX region [mem 0x150000000-0x33fffffff] cannot be hotremoved until the next reboot Now, we can reconfigure the namespace: [root@localhost ~]# ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax [ 131.409351] nd_pmem namespace0.0: could not reserve region [mem 0x140000000-0x33fffffff]dax [ 131.410147] nd_pmem: probe of namespace0.0 failed with error -16namespace0.0 --mode=devdax ... This fails as expected due to the busy memory resource, and the memory cannot be used. However, the dax0.0 device is removed, and along its name. The name of the memory resource now points at freed memory (name of the device): [root@localhost ~]# cat /proc/iomem ... 140000000-33fffffff : Persistent Memory 140000000-1481fffff : namespace0.0 150000000-33fffffff : �_�^7_��/_��wR��WQ���^��� ... 150000000-33fffffff : System RAM We have to make sure to duplicate the string. While at it, remove the superfluous setting of the name and fixup a stale comment. Fixes: 9f960da72b25 ("device-dax: "Hotremove" persistent memory that is used like normal RAM") Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Cc: Dan Williams Cc: Vishal Verma Cc: Dave Jiang Cc: Pavel Tatashin Cc: Andrew Morton Cc: [5.3] Link: http://lkml.kernel.org/r/20200508084217.9160-2-david@redhat.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/dax/kmem.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c index 3d0a7e702c94..1e678bdf5aed 100644 --- a/drivers/dax/kmem.c +++ b/drivers/dax/kmem.c @@ -22,6 +22,7 @@ int dev_dax_kmem_probe(struct device *dev) resource_size_t kmem_size; resource_size_t kmem_end; struct resource *new_res; + const char *new_res_name; int numa_node; int rc; @@ -48,11 +49,16 @@ int dev_dax_kmem_probe(struct device *dev) kmem_size &= ~(memory_block_size_bytes() - 1); kmem_end = kmem_start + kmem_size; - /* Region is permanently reserved. Hot-remove not yet implemented. */ - new_res = request_mem_region(kmem_start, kmem_size, dev_name(dev)); + new_res_name = kstrdup(dev_name(dev), GFP_KERNEL); + if (!new_res_name) + return -ENOMEM; + + /* Region is permanently reserved if hotremove fails. */ + new_res = request_mem_region(kmem_start, kmem_size, new_res_name); if (!new_res) { dev_warn(dev, "could not reserve region [%pa-%pa]\n", &kmem_start, &kmem_end); + kfree(new_res_name); return -EBUSY; } @@ -63,12 +69,12 @@ int dev_dax_kmem_probe(struct device *dev) * unknown to us that will break add_memory() below. */ new_res->flags = IORESOURCE_SYSTEM_RAM; - new_res->name = dev_name(dev); rc = add_memory(numa_node, new_res->start, resource_size(new_res)); if (rc) { release_resource(new_res); kfree(new_res); + kfree(new_res_name); return rc; } dev_dax->dax_kmem_res = new_res; @@ -83,6 +89,7 @@ static int dev_dax_kmem_remove(struct device *dev) struct resource *res = dev_dax->dax_kmem_res; resource_size_t kmem_start = res->start; resource_size_t kmem_size = resource_size(res); + const char *res_name = res->name; int rc; /* @@ -102,6 +109,7 @@ static int dev_dax_kmem_remove(struct device *dev) /* Release and free dax resources */ release_resource(res); kfree(res); + kfree(res_name); dev_dax->dax_kmem_res = NULL; return 0; -- 2.25.1