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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF00CC433EF for ; Mon, 4 Oct 2021 06:09:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E2EE61360 for ; Mon, 4 Oct 2021 06:09:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232615AbhJDGKw (ORCPT ); Mon, 4 Oct 2021 02:10:52 -0400 Received: from linux.microsoft.com ([13.77.154.182]:34230 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231935AbhJDGKw (ORCPT ); Mon, 4 Oct 2021 02:10:52 -0400 Received: from sequoia.work.tihix.com (162-237-133-238.lightspeed.rcsntx.sbcglobal.net [162.237.133.238]) by linux.microsoft.com (Postfix) with ESMTPSA id EB31720B861E; Sun, 3 Oct 2021 23:09:02 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com EB31720B861E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1633327743; bh=THyLkAVaDs1Hb92aOse98gBjcNS/im3qub3b4KePinA=; h=From:To:Cc:Subject:Date:From; b=i+YokozB2sWf+jfr4g4qRR+P8mPaGVgPum+tXZWOEsAZ+R22OlXDCUy5XbRObxXEv exyzKR5zFEwUz/BUaWxBHY9hHEc4AyOwvc3NhKOfOWmHnKVi5IPdjdJfRJppXxY49k sh8rY3g1BAedoeMia9cDVJYJeZam7CN3gR9P4N/s= From: Tyler Hicks To: stable@vger.kernel.org Cc: Rob Herring , Anders Roxell , Bjorn Helgaas , Lorenzo Pieralisi , Arnd Bergmann Subject: [PATCH 5.4] PCI: Fix pci_host_bridge struct device release/free handling Date: Mon, 4 Oct 2021 01:08:38 -0500 Message-Id: <20211004060838.678790-1-tyhicks@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rob Herring commit 9885440b16b8fc1dd7275800fd28f56a92f60896 upstream. The PCI code has several paths where the struct pci_host_bridge is freed directly. This is wrong because it contains a struct device which is refcounted and should be freed using put_device(). This can result in use-after-free errors. I think this problem has existed since 2012 with commit 7b5436635800 ("PCI: add generic device into pci_host_bridge struct"). It generally hasn't mattered as most host bridge drivers are still built-in and can't unbind. The problem is a struct device should never be freed directly once device_initialize() is called and a ref is held, but that doesn't happen until pci_register_host_bridge(). There's then a window between allocating the host bridge and pci_register_host_bridge() where kfree should be used. This is fragile and requires callers to do the right thing. To fix this, we need to split device_register() into device_initialize() and device_add() calls, so that the host bridge struct is always freed by using a put_device(). devm_pci_alloc_host_bridge() is using devm_kzalloc() to allocate struct pci_host_bridge which will be freed directly. Instead, we can use a custom devres action to call put_device(). Link: https://lore.kernel.org/r/20200513223859.11295-2-robh@kernel.org Reported-by: Anders Roxell Tested-by: Anders Roxell Signed-off-by: Rob Herring Signed-off-by: Bjorn Helgaas Reviewed-by: Lorenzo Pieralisi Acked-by: Arnd Bergmann [tyhicks: Minor contextual change in pci_init_host_bridge() due to the lack of a native_dpc member in the pci_host_bridge struct. It was added in v5.7 with commit ac1c8e35a326 ("PCI/DPC: Add Error Disconnect Recover (EDR) support")] Signed-off-by: Tyler Hicks --- This commit has been identified as a fix for random memory corruption that we're experiencing in production. The memory corruption is easily reproducible on 5.4.150 and we get a nice KASAN splat that led us to discovering the upstream fix that wasn't marked for stable inclusion. I don't see any obvious reasons why this wouldn't be a valid linux-5.4.y candidate and hope we can get it applied there. I've verified that the KASAN splat goes away and I don't see any other evidence of the memory corruption issue once this commit is applied to 5.4.150. drivers/pci/probe.c | 36 +++++++++++++++++++----------------- drivers/pci/remove.c | 2 +- 2 files changed, 20 insertions(+), 18 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index f28213b62527..a41d04c57642 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -564,7 +564,7 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus *parent) return b; } -static void devm_pci_release_host_bridge_dev(struct device *dev) +static void pci_release_host_bridge_dev(struct device *dev) { struct pci_host_bridge *bridge = to_pci_host_bridge(dev); @@ -573,12 +573,7 @@ static void devm_pci_release_host_bridge_dev(struct device *dev) pci_free_resource_list(&bridge->windows); pci_free_resource_list(&bridge->dma_ranges); -} - -static void pci_release_host_bridge_dev(struct device *dev) -{ - devm_pci_release_host_bridge_dev(dev); - kfree(to_pci_host_bridge(dev)); + kfree(bridge); } static void pci_init_host_bridge(struct pci_host_bridge *bridge) @@ -597,6 +592,8 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge) bridge->native_shpc_hotplug = 1; bridge->native_pme = 1; bridge->native_ltr = 1; + + device_initialize(&bridge->dev); } struct pci_host_bridge *pci_alloc_host_bridge(size_t priv) @@ -614,17 +611,25 @@ struct pci_host_bridge *pci_alloc_host_bridge(size_t priv) } EXPORT_SYMBOL(pci_alloc_host_bridge); +static void devm_pci_alloc_host_bridge_release(void *data) +{ + pci_free_host_bridge(data); +} + struct pci_host_bridge *devm_pci_alloc_host_bridge(struct device *dev, size_t priv) { + int ret; struct pci_host_bridge *bridge; - bridge = devm_kzalloc(dev, sizeof(*bridge) + priv, GFP_KERNEL); + bridge = pci_alloc_host_bridge(priv); if (!bridge) return NULL; - pci_init_host_bridge(bridge); - bridge->dev.release = devm_pci_release_host_bridge_dev; + ret = devm_add_action_or_reset(dev, devm_pci_alloc_host_bridge_release, + bridge); + if (ret) + return NULL; return bridge; } @@ -632,10 +637,7 @@ EXPORT_SYMBOL(devm_pci_alloc_host_bridge); void pci_free_host_bridge(struct pci_host_bridge *bridge) { - pci_free_resource_list(&bridge->windows); - pci_free_resource_list(&bridge->dma_ranges); - - kfree(bridge); + put_device(&bridge->dev); } EXPORT_SYMBOL(pci_free_host_bridge); @@ -866,7 +868,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) if (err) goto free; - err = device_register(&bridge->dev); + err = device_add(&bridge->dev); if (err) { put_device(&bridge->dev); goto free; @@ -933,7 +935,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) unregister: put_device(&bridge->dev); - device_unregister(&bridge->dev); + device_del(&bridge->dev); free: kfree(bus); @@ -2945,7 +2947,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus, return bridge->bus; err_out: - kfree(bridge); + put_device(&bridge->dev); return NULL; } EXPORT_SYMBOL_GPL(pci_create_root_bus); diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c index e9c6b120cf45..95dec03d9f2a 100644 --- a/drivers/pci/remove.c +++ b/drivers/pci/remove.c @@ -160,6 +160,6 @@ void pci_remove_root_bus(struct pci_bus *bus) host_bridge->bus = NULL; /* remove the host bridge */ - device_unregister(&host_bridge->dev); + device_del(&host_bridge->dev); } EXPORT_SYMBOL_GPL(pci_remove_root_bus); -- 2.25.1