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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, 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 705B4C43387 for ; Tue, 15 Jan 2019 17:32:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4C78320859 for ; Tue, 15 Jan 2019 17:32:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388351AbfAORcI (ORCPT ); Tue, 15 Jan 2019 12:32:08 -0500 Received: from ale.deltatee.com ([207.54.116.67]:53146 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726022AbfAORcH (ORCPT ); Tue, 15 Jan 2019 12:32:07 -0500 Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gjSZK-0000Ss-Fh; Tue, 15 Jan 2019 10:32:07 -0700 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.89) (envelope-from ) id 1gjSZJ-0003sE-TW; Tue, 15 Jan 2019 10:32:05 -0700 From: Logan Gunthorpe To: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas Cc: Stephen Bates , Logan Gunthorpe , Jarkko Nikula Date: Tue, 15 Jan 2019 10:32:03 -0700 Message-Id: <20190115173203.14850-1-logang@deltatee.com> X-Mailer: git-send-email 2.19.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, bhelgaas@google.com, sbates@raithlin.com, logang@deltatee.com, jarkko.nikula@linux.intel.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [PATCH] PCI: fix using __initdata memory after free in disable_acs_redir parameter X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The disable_acs_redir parameter stores a pointer to the string passed to pci_setup(). However, the string passed to PCI setup is actually a temporary copy allocated in static __initdata memory. After init, once the memory is freed, it is no longer valid to reference this pointer. This bug was noticed in v5.0-rc1 after a change in commit c5eb1190074c ("PCI / PM: Allow runtime PM without callback functions") caused pci_disable_acs_redir() to be called during shutdown which manifested as an unable to handle kernel paging request at: RIP: 0010:pci_enable_acs+0x3f/0x1e0 Call Trace: pci_restore_state.part.44+0x159/0x3c0 pci_restore_standard_config+0x33/0x40 pci_pm_runtime_resume+0x2b/0xd0 ? pci_restore_standard_config+0x40/0x40 __rpm_callback+0xbc/0x1b0 rpm_callback+0x1f/0x70 ? pci_restore_standard_config+0x40/0x40 rpm_resume+0x4f9/0x710 ? pci_conf1_read+0xb6/0xf0 ? pci_conf1_write+0xb2/0xe0 __pm_runtime_resume+0x47/0x70 pci_device_shutdown+0x1e/0x60 device_shutdown+0x14a/0x1f0 kernel_restart+0xe/0x50 __do_sys_reboot+0x1ee/0x210 ? __fput+0x144/0x1d0 do_writev+0x5e/0xf0 ? do_writev+0x5e/0xf0 do_syscall_64+0x48/0xf0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 It was also likely possible to trigger this bug when hotplugging PCI devices. To fix this, instead of storing a pointer, we use kstrdup to copy the disable_acs_redir_param to its own buffer which will never be freed. Fixes: aaca43fda742 ("PCI: Add "pci=disable_acs_redir=" parameter for peer-to-peer support") Signed-off-by: Logan Gunthorpe Cc: Jarkko Nikula Cc: Bjorn Helgaas --- drivers/pci/pci.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index c9d8e3c837de..c25acace7d91 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -6195,7 +6195,8 @@ static int __init pci_setup(char *str) } else if (!strncmp(str, "pcie_scan_all", 13)) { pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS); } else if (!strncmp(str, "disable_acs_redir=", 18)) { - disable_acs_redir_param = str + 18; + disable_acs_redir_param = + kstrdup(str + 18, GFP_KERNEL); } else { printk(KERN_ERR "PCI: Unknown option `%s'\n", str); -- 2.19.0