From: Krzysztof Wilczyński Date: Fri, 8 May 2026 04:35:33 +0000 (+0000) Subject: alpha/PCI: Fix __pci_mmap_fits() overflow for zero-length BARs X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=802a3b3f470b9bc1148f26e01fc9cbfeb4dfcb57;p=thirdparty%2Flinux.git alpha/PCI: Fix __pci_mmap_fits() overflow for zero-length BARs 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: 10a0ef39fbd1 ("PCI/alpha: pci sysfs resources") Signed-off-by: Krzysztof Wilczyński Signed-off-by: Bjorn Helgaas Tested-by: Magnus Lindholm Tested-by: Shivaprasad G Bhat Reviewed-by: Ilpo Järvinen Acked-by: Magnus Lindholm Link: https://patch.msgid.link/20260508043543.217179-15-kwilczynski@kernel.org --- diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c index 5c29f1d2821c..8802f955256e 100644 --- a/arch/alpha/kernel/pci-sysfs.c +++ b/arch/alpha/kernel/pci-sysfs.c @@ -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;