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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 <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>
CC: stable@vger.kernel.org
This commit is contained in:
Michel Dänzer 2015-01-19 17:53:20 +09:00 committed by Bjorn Helgaas
parent 97bf6af1f9
commit 16b036af31
1 changed files with 4 additions and 3 deletions
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7
drivers/pci/rom.c
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@ -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 */