From patchwork Thu Aug 24 09:14:47 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Mackerras X-Patchwork-Id: 9919619 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 D25ED60349 for ; Thu, 24 Aug 2017 09:14:57 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C65EF28BA7 for ; Thu, 24 Aug 2017 09:14:57 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BAE7F28BAD; Thu, 24 Aug 2017 09:14:57 +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=-7.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_HI autolearn=ham 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 352A228BA7 for ; Thu, 24 Aug 2017 09:14:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751951AbdHXJOx (ORCPT ); Thu, 24 Aug 2017 05:14:53 -0400 Received: from ozlabs.org ([103.22.144.67]:60895 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751260AbdHXJOw (ORCPT ); Thu, 24 Aug 2017 05:14:52 -0400 Received: by ozlabs.org (Postfix, from userid 1003) id 3xdJXV4xh9z9sPk; Thu, 24 Aug 2017 19:14:50 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ozlabs.org; s=201707; t=1503566090; bh=tB9ATbKQefwWcnBKxAiHeuTcErUYsH4rN5bFXSmE2JA=; h=Date:From:To:Cc:Subject:From; b=g9aEKjMrpw7QWfk37s5nxp7hYxcIs+qV9YhU+jMl8ONWj6AuqLaYBDeo/CKa6/eJ9 IiPPX/YSd2StY/bxB5UkRt/wJIEyGifGbXrV3xSM3OzEKIk9Vu4jgCNPy96Yfo0HlP jvPnbRKmA97O6w4xrquQUZmykveT1163rBh2e4B4SSDwZhFm6VOohtT3TKE8To2iMH TjbU9YTGDKICQWTEBcsvyiskc23FRncLm/bAPEziWnua6p5nAvKr8NM0q1iIa6mkD/ IaFhaql9F2b/up/RXh5gmXlw4oesINFBNv/GDzy5SotMwLeEggxl8UQ7Z9Flh9WITG Xz9ptyXGhEYcQ== Date: Thu, 24 Aug 2017 19:14:47 +1000 From: Paul Mackerras To: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: nixiaoming , David Hildenbrand , David Gibson Subject: [PATCH really v2] KVM: PPC: Book3S: Fix race and leak in kvm_vm_ioctl_create_spapr_tce() Message-ID: <20170824091447.GG27401@fergus.ozlabs.ibm.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Nixiaoming pointed out that there is a memory leak in kvm_vm_ioctl_create_spapr_tce() if the call to anon_inode_getfd() fails; the memory allocated for the kvmppc_spapr_tce_table struct is not freed, and nor are the pages allocated for the iommu tables. In addition, we have already incremented the process's count of locked memory pages, and this doesn't get restored on error. David Hildenbrand pointed out that there is a race in that the function checks early on that there is not already an entry in the stt->iommu_tables list with the same LIOBN, but an entry with the same LIOBN could get added between then and when the new entry is added to the list. This fixes all three problems. To simplify things, we now call anon_inode_getfd() before placing the new entry in the list. The check for an existing entry is done while holding the kvm->lock mutex, immediately before adding the new entry to the list. Finally, on failure we now call kvmppc_account_memlimit to decrement the process's count of locked memory pages. Reported-by: Nixiaoming Reported-by: David Hildenbrand Signed-off-by: Paul Mackerras Reviewed-by: David Gibson Reviewed-by: David Hildenbrand Reviewed-by: nixiaoming --- v2: Don't overwrite stt in loop over spapr_tce_tables arch/powerpc/kvm/book3s_64_vio.c | 56 ++++++++++++++++++++++++---------------- 1 file changed, 34 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index a160c14..53766e2 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -294,32 +294,26 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, struct kvm_create_spapr_tce_64 *args) { struct kvmppc_spapr_tce_table *stt = NULL; + struct kvmppc_spapr_tce_table *siter; unsigned long npages, size; int ret = -ENOMEM; int i; + int fd = -1; if (!args->size) return -EINVAL; - /* Check this LIOBN hasn't been previously allocated */ - list_for_each_entry(stt, &kvm->arch.spapr_tce_tables, list) { - if (stt->liobn == args->liobn) - return -EBUSY; - } - size = _ALIGN_UP(args->size, PAGE_SIZE >> 3); npages = kvmppc_tce_pages(size); ret = kvmppc_account_memlimit(kvmppc_stt_pages(npages), true); - if (ret) { - stt = NULL; - goto fail; - } + if (ret) + return ret; ret = -ENOMEM; stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *), GFP_KERNEL); if (!stt) - goto fail; + goto fail_acct; stt->liobn = args->liobn; stt->page_shift = args->page_shift; @@ -334,24 +328,42 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, goto fail; } - kvm_get_kvm(kvm); + ret = fd = anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops, + stt, O_RDWR | O_CLOEXEC); + if (ret < 0) + goto fail; mutex_lock(&kvm->lock); - list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables); + + /* Check this LIOBN hasn't been previously allocated */ + ret = 0; + list_for_each_entry(siter, &kvm->arch.spapr_tce_tables, list) { + if (siter->liobn == args->liobn) { + ret = -EBUSY; + break; + } + } + + if (!ret) { + list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables); + kvm_get_kvm(kvm); + } mutex_unlock(&kvm->lock); - return anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops, - stt, O_RDWR | O_CLOEXEC); + if (!ret) + return fd; -fail: - if (stt) { - for (i = 0; i < npages; i++) - if (stt->pages[i]) - __free_page(stt->pages[i]); + put_unused_fd(fd); - kfree(stt); - } + fail: + for (i = 0; i < npages; i++) + if (stt->pages[i]) + __free_page(stt->pages[i]); + + kfree(stt); + fail_acct: + kvmppc_account_memlimit(kvmppc_stt_pages(npages), false); return ret; }