Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755317AbbEECgx (ORCPT ); Mon, 4 May 2015 22:36:53 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50761 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751763AbbEEBVz (ORCPT ); Mon, 4 May 2015 21:21:55 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Federico" , "=?UTF-8?q?Michel=20D=C3=A4nzer?=" , "Bjorn Helgaas" , "Alex Deucher" Date: Tue, 05 May 2015 02:16:39 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 015/221] PCI: Fix infinite loop with ROM image of size 0 In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1829 Lines: 55 3.2.69-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Michel Dänzer 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: Ben Hutchings --- drivers/pci/rom.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/pci/rom.c +++ b/drivers/pci/rom.c @@ -69,6 +69,7 @@ size_t pci_get_rom_size(struct pci_dev * { void __iomem *image; int last_image; + unsigned length; image = rom; do { @@ -91,9 +92,9 @@ size_t pci_get_rom_size(struct pci_dev * 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 */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/