From: Michel Dänzer Date: Mon, 19 Jan 2015 08:53:20 +0000 (+0900) Subject: PCI: Fix infinite loop with ROM image of size 0 X-Git-Tag: firefly_0821_release~176^2~2382^2~4^4 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=16b036af31e1456cb69243a5a0c9ef801ecd1f17;p=firefly-linux-kernel-4.4.55.git PCI: Fix infinite loop with ROM image of size 0 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 CC: stable@vger.kernel.org --- diff --git a/drivers/pci/rom.c b/drivers/pci/rom.c index f955edb9bea7..eb0ad530dc43 100644 --- a/drivers/pci/rom.c +++ b/drivers/pci/rom.c @@ -71,6 +71,7 @@ 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 { @@ -93,9 +94,9 @@ 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 */