From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753284AbbCaTtb (ORCPT ); Tue, 31 Mar 2015 15:49:31 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:39089 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753140AbbCaTtS (ORCPT ); Tue, 31 Mar 2015 15:49:18 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: =?UTF-8?q?Michel=20D=C3=A4nzer?= , Bjorn Helgaas , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 046/143] PCI: Fix infinite loop with ROM image of size 0 Date: Tue, 31 Mar 2015 12:46:51 -0700 Message-Id: <1427831308-1854-47-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1427831308-1854-1-git-send-email-kamal@canonical.com> References: <1427831308-1854-1-git-send-email-kamal@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt18 -stable review patch. If anyone has any objections, please let me know. ------------------ From: =?UTF-8?q?Michel=20D=C3=A4nzer?= commit 16b036af31e1456cb69243a5a0c9ef801ecd1f17 upstream. If the image size would ever read as 0, pci_get_rom_size() could keep processing the same image over and over again. Exit the loop if we ever read a length of zero. This fixes a soft lockup on boot when the radeon driver calls pci_get_rom_size() on an AMD Radeon R7 250X PCIe discrete graphics card. [bhelgaas: changelog, reference] Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1386973 Reported-by: Federico Signed-off-by: Michel Dänzer Signed-off-by: Bjorn Helgaas Reviewed-by: Alex Deucher Signed-off-by: Kamal Mostafa --- drivers/pci/rom.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c index c5d0a08..d6d4997 100644 --- a/drivers/pci/rom.c +++ b/drivers/pci/rom.c @@ -69,6 +69,7 @@ size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size) { void __iomem *image; int last_image; + unsigned length; image = rom; do { @@ -91,9 +92,9 @@ size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size) if (readb(pds + 3) != 'R') break; last_image = readb(pds + 21) & 0x80; - /* this length is reliable */ - image += readw(pds + 16) * 512; - } while (!last_image); + length = readw(pds + 16); + image += length * 512; + } while (length && !last_image); /* never return a size larger than the PCI resource window */ /* there are known ROMs that get the size wrong */ -- 1.9.1