| From | lizf@kernel ... | Subject | [PATCH 3.4 011/172] PCI: Fix infinite loop with ROM image of size 0 | Date | Tue, 16 Jun 2015 16:34:25 +0800 |
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From: Michel Dänzer <michel.daenzer@amd.com>
3.4.108-rc1 review patch. If anyone has any objections, please let me know.
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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 <federicotg@gmail.com> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Zefan Li <lizefan@huawei.com> --- 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 48ebdb2..e31659c 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
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