[{"id":3676674,"web_url":"http://patchwork.ozlabs.org/comment/3676674/","msgid":"","list_archive_url":null,"date":"2026-04-13T11:44:29","subject":"Re: [PATCH v4 15/24] alpha/PCI: Fix __pci_mmap_fits() overflow for\n zero-length BARs","submitter":{"id":83553,"url":"http://patchwork.ozlabs.org/api/people/83553/","name":"Ilpo Järvinen","email":"ilpo.jarvinen@linux.intel.com"},"content":"On Sat, 11 Apr 2026, Krzysztof Wilczyński wrote:\n\n> Currently, __pci_mmap_fits() computes the BAR size using\n> pci_resource_len() - 1, which wraps to a large value when the\n> BAR length is zero, causing the bounds check to incorrectly\n> succeed.\n> \n> Thus, add an early return for empty resources.\n> \n> Fixes: 10a0ef39fbd1 (\"PCI/alpha: pci sysfs resources\")\n> Signed-off-by: Krzysztof Wilczyński \n> ---\n> arch/alpha/kernel/pci-sysfs.c | 6 +++++-\n> 1 file changed, 5 insertions(+), 1 deletion(-)\n> \n> diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c\n> index 6c011dab326d..2748000a7486 100644\n> --- a/arch/alpha/kernel/pci-sysfs.c\n> +++ b/arch/alpha/kernel/pci-sysfs.c\n> @@ -37,12 +37,16 @@ static int hose_mmap_page_range(struct pci_controller *hose,\n> static int __pci_mmap_fits(struct pci_dev *pdev, int num,\n> \t\t\t struct vm_area_struct *vma, int sparse)\n> {\n> +\tresource_size_t len = pci_resource_len(pdev, num);\n> \tunsigned long nr, start, size;\n> \tint shift = sparse ? 5 : 0;\n> \n> +\tif (!len)\n> +\t\treturn 0;\n> +\n> \tnr = vma_pages(vma);\n> \tstart = vma->vm_pgoff;\n> -\tsize = ((pci_resource_len(pdev, num) - 1) >> (PAGE_SHIFT - shift)) + 1;\n> +\tsize = ((len - 1) >> (PAGE_SHIFT - shift)) + 1;\n> \n> \tif (start < size && size - start >= nr)\n> \t\treturn 1;\n> \n\nReviewed-by: Ilpo Järvinen ","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256\n header.s=Intel header.b=Xrt87pcC;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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