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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 32FA3C432BE for ; Tue, 24 Aug 2021 17:04:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16822613AB for ; Tue, 24 Aug 2021 17:04:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239498AbhHXRET (ORCPT ); Tue, 24 Aug 2021 13:04:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:39458 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238957AbhHXRBa (ORCPT ); Tue, 24 Aug 2021 13:01:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D855A61529; Tue, 24 Aug 2021 16:57:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629824276; bh=kn+He9GX/FRV0b+ohhAqU0CS54NwO0fPdrsdZTgbegU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MeUKifIKS8Hs9KFqN9vA7+z5tCiyTga4N+vo9tKytt90fRewNuiE947+mBkK6Vpwa hVy+WXjMvaugQnjCLGqPyWQnacg3KtJd/EdwiAY3WAWnyO/BpNIkFNAz2CUeUHdGJM IyGXaBc//wGr/KAFPJD/C37DGikNogjeiE5cRYukCHM3dmhbu9/wrO2VRojuahjDcI 0y0pdonjv2YMMoadLqTnaUSaUQK39msts9AWaORjaapw92xJ8f1dqYRDKIJKgtArgd PH2CksS7JM3bQq1wDAE7eXwzJYjcIVTtMzgPHjCNdEnzLdcAwsBaMHTlfPNY1/OT1i X6+KREMejwAaA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Niklas Schnelle , Matthew Rosato , Vasily Gorbik , Sasha Levin Subject: [PATCH 5.13 111/127] s390/pci: fix use after free of zpci_dev Date: Tue, 24 Aug 2021 12:55:51 -0400 Message-Id: <20210824165607.709387-112-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824165607.709387-1-sashal@kernel.org> References: <20210824165607.709387-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.13.13-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.13.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.13.13-rc1 X-KernelTest-Deadline: 2021-08-26T16:55+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Niklas Schnelle [ Upstream commit 2a671f77ee49f3e78997b77fdee139467ff6a598 ] The struct pci_dev uses reference counting but zPCI assumed erroneously that the last reference would always be the local reference after calling pci_stop_and_remove_bus_device(). This is usually the case but not how reference counting works and thus inherently fragile. In fact one case where this causes a NULL pointer dereference when on an SRIOV device the function 0 was hot unplugged before another function of the same multi-function device. In this case the second function's pdev->sriov->dev reference keeps the struct pci_dev of function 0 alive even after the unplug. This bug was previously hidden by the fact that we were leaking the struct pci_dev which in turn means that it always outlived the struct zpci_dev. This was fixed in commit 0b13525c20fe ("s390/pci: fix leak of PCI device structure") exposing the broken behavior. Fix this by accounting for the long living reference a struct pci_dev has to its underlying struct zpci_dev via the zbus->function[] array and only release that in pcibios_release_device() ensuring that the struct pci_dev is not left with a dangling reference. This is a minimal fix in the future it would probably better to use fine grained reference counting for struct zpci_dev. Fixes: 05bc1be6db4b2 ("s390/pci: create zPCI bus") Cc: stable@vger.kernel.org Reviewed-by: Matthew Rosato Signed-off-by: Niklas Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin --- arch/s390/pci/pci.c | 6 ++++++ arch/s390/pci/pci_bus.h | 5 +++++ 2 files changed, 11 insertions(+) diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c index b0993e05affe..8fcb7ecb7225 100644 --- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -560,9 +560,12 @@ static void zpci_cleanup_bus_resources(struct zpci_dev *zdev) int pcibios_add_device(struct pci_dev *pdev) { + struct zpci_dev *zdev = to_zpci(pdev); struct resource *res; int i; + /* The pdev has a reference to the zdev via its bus */ + zpci_zdev_get(zdev); if (pdev->is_physfn) pdev->no_vf_scan = 1; @@ -582,7 +585,10 @@ int pcibios_add_device(struct pci_dev *pdev) void pcibios_release_device(struct pci_dev *pdev) { + struct zpci_dev *zdev = to_zpci(pdev); + zpci_unmap_resources(pdev); + zpci_zdev_put(zdev); } int pcibios_enable_device(struct pci_dev *pdev, int mask) diff --git a/arch/s390/pci/pci_bus.h b/arch/s390/pci/pci_bus.h index b877a97e6745..e359d2686178 100644 --- a/arch/s390/pci/pci_bus.h +++ b/arch/s390/pci/pci_bus.h @@ -22,6 +22,11 @@ static inline void zpci_zdev_put(struct zpci_dev *zdev) kref_put(&zdev->kref, zpci_release_device); } +static inline void zpci_zdev_get(struct zpci_dev *zdev) +{ + kref_get(&zdev->kref); +} + int zpci_alloc_domain(int domain); void zpci_free_domain(int domain); int zpci_setup_bus_resources(struct zpci_dev *zdev, -- 2.30.2