From patchwork Wed Jul 13 09:35:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 12916386 X-Patchwork-Delegate: bhelgaas@google.com 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4157C43334 for ; Wed, 13 Jul 2022 09:36:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236097AbiGMJgX (ORCPT ); Wed, 13 Jul 2022 05:36:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236158AbiGMJgB (ORCPT ); Wed, 13 Jul 2022 05:36:01 -0400 Received: from xavier.telenet-ops.be (xavier.telenet-ops.be [IPv6:2a02:1800:120:4::f00:14]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5F872250E for ; Wed, 13 Jul 2022 02:35:56 -0700 (PDT) Received: from ramsan.of.borg ([84.195.186.194]) by xavier.telenet-ops.be with bizsmtp id uZbt2700R4C55Sk01Zbtd4; Wed, 13 Jul 2022 11:35:54 +0200 Received: from rox.of.borg ([192.168.97.57]) by ramsan.of.borg with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1oBYmf-003LRy-7N; Wed, 13 Jul 2022 11:35:53 +0200 Received: from geert by rox.of.borg with local (Exim 4.93) (envelope-from ) id 1oBYme-00B78G-Ol; Wed, 13 Jul 2022 11:35:52 +0200 From: Geert Uytterhoeven To: Bjorn Helgaas , Kai-Heng Feng Cc: Johannes Berg , Rob Herring , Thierry Reding , linux-pci@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] PCI: Fix dropping valid root bus resources with .end = zero Date: Wed, 13 Jul 2022 11:35:50 +0200 Message-Id: <9c41a4372b27420c732ff5599d823e363de00c6d.1657704829.git.geert+renesas@glider.be> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On r8a7791/koelsch: kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak) # cat /sys/kernel/debug/kmemleak unreferenced object 0xc3a34e00 (size 64): comm "swapper/0", pid 1, jiffies 4294937460 (age 199.080s) hex dump (first 32 bytes): b4 5d 81 f0 b4 5d 81 f0 c0 b0 a2 c3 00 00 00 00 .]...].......... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] __kmalloc+0xf0/0x140 [<34bd6bc0>] resource_list_create_entry+0x18/0x38 [<767046bc>] pci_add_resource_offset+0x20/0x68 [] devm_of_pci_get_host_bridge_resources.constprop.0+0xb0/0x390 When coalescing two resources for a contiguous aperture, the first resource is enlarged to cover the full contiguous range, while the second resource is marked invalid. This invalidation is done by clearing the flags, start, and end members. When adding the initial resources to the bus later, invalid resources are skipped. Unfortunately, the check for an invalid resource considers only the end member, causing false positives. E.g. on r8a7791/koelsch, root bus resource 0 ("bus 00") is skipped, and no longer registered with pci_bus_insert_busn_res() (causing the memory leak), nor printed: pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges: pci-rcar-gen2 ee090000.pci: MEM 0x00ee080000..0x00ee08ffff -> 0x00ee080000 pci-rcar-gen2 ee090000.pci: PCI: revision 11 pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00 -pci_bus 0000:00: root bus resource [bus 00] pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff] Fix this by only skipping resources where all of the flags, start, and end members are zero. Fixes: 7c3855c423b17f6c ("PCI: Coalesce host bridge contiguous apertures") Signed-off-by: Geert Uytterhoeven Tested-by: Niklas Schnelle Acked-by: Kai-Heng Feng --- Is there any side effect of not registering the root bus resource with pci_bus_insert_busn_res()? This is the resource created by of_pci_parse_bus_range(), and thus affects any DT platforms using "bus-range = <0 0>". Perhaps checking for "!res->flags" would be sufficient? I assume this still causes memory leaks on systems where resources are coalesced, as the second resource of a contiguous aperture is no longer referenced? Perhaps instead of clearing the resource, it should be removed from the list (and freed? is it actually safe to do that?)? Apparently Johannes had identified the bug before, but didn't realize the full impact... https://lore.kernel.org/r/5331e942ff28bb191d62bb403b03ceb7d750856c.camel@sipsolutions.net/ --- drivers/pci/probe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 17a969942d37033a..be628798d279ada0 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -994,7 +994,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) resource_list_for_each_entry_safe(window, n, &resources) { offset = window->offset; res = window->res; - if (!res->end) + if (!res->flags && !res->start && !res->end) continue; list_move_tail(&window->node, &bridge->windows);