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alpha/PCI: Fix __pci_mmap_fits() overflow for zero-length BARs

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Currently, __pci_mmap_fits() computes the BAR size using
"pci_resource_len() - 1", which wraps to a large value when the BAR length
is zero, causing the bounds check to incorrectly succeed.

Add an early return for empty resources.

Fixes: 10a0ef39fb ("PCI/alpha: pci sysfs resources")
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Magnus Lindholm <linmag7@gmail.com>
Tested-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Magnus Lindholm <linmag7@gmail.com>
Link: https://patch.msgid.link/20260508043543.217179-15-kwilczynski@kernel.org
This commit is contained in:
Krzysztof Wilczyński 2026-05-08 04:35:33 +00:00 committed by Bjorn Helgaas
parent 30d01a8c3a
commit 802a3b3f47
1 changed files with 5 additions and 1 deletions
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6
arch/alpha/kernel/pci-sysfs.c
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@ -37,12 +37,16 @@ static int hose_mmap_page_range(struct pci_controller *hose,
static int __pci_mmap_fits(struct pci_dev *pdev, int num,
struct vm_area_struct *vma, int sparse)
{
resource_size_t len = pci_resource_len(pdev, num);
unsigned long nr, start, size;
int shift = sparse ? 5 : 0;
if (!len)
return 0;
nr = vma_pages(vma);
start = vma->vm_pgoff;
size = ((pci_resource_len(pdev, num) - 1) >> (PAGE_SHIFT - shift)) + 1;
size = ((len - 1) >> (PAGE_SHIFT - shift)) + 1;
if (start < size && size - start >= nr)
return 1;