[{"id":3675823,"web_url":"http://patchwork.ozlabs.org/comment/3675823/","msgid":"<66eb23bf-1995-363f-78e6-f5a397a063a2@linux.intel.com>","date":"2026-04-10T11:14:55","subject":"Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()","submitter":{"id":83553,"url":"http://patchwork.ozlabs.org/api/people/83553/","name":"Ilpo Järvinen","email":"ilpo.jarvinen@linux.intel.com"},"content":"On Fri, 10 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> Also, remove the WARN() that fires when userspace attempts to\n> mmap beyond the BAR bounds. The check still returns 0 to reject\n> the mapping, but the warning is excessive for normal operation.\n> \n> A similar warning was removed from the PCI core in the commit\n> 3b519e4ea618 (\"PCI: fix size checks for mmap() on /proc/bus/pci files\").\n\nThis looks like entirely separate two changes to me which just happen \nwithin the same context.\n\n> Signed-off-by: Krzysztof Wilczyński \n> ---\n> arch/alpha/kernel/pci-sysfs.c | 14 ++++++--------\n> 1 file changed, 6 insertions(+), 8 deletions(-)\n> \n> diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c\n> index 7aac5e76dcd6..867199b988de 100644\n> --- a/arch/alpha/kernel/pci-sysfs.c\n> +++ b/arch/alpha/kernel/pci-sysfs.c\n> @@ -37,20 +37,18 @@ 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> -\tWARN(1, \"process \\\"%s\\\" tried to map%s 0x%08lx-0x%08lx on %s BAR %d \"\n> -\t\t\"(size 0x%08lx)\\n\",\n> -\t\tcurrent->comm, sparse ? \" sparse\" : \"\", start, start + nr,\n> -\t\tpci_name(pdev), num, size);\n> -\treturn 0;\n> +\treturn start < size && size - start >= nr;\n> }\n> \n> /**\n>","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.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=CkN7lzyZ;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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a=\"94415840\"","E=Sophos;i=\"6.23,171,1770624000\";\n d=\"scan'208\";a=\"94415840\"","E=Sophos;i=\"6.23,171,1770624000\";\n d=\"scan'208\";a=\"267023344\""],"X-ExtLoop1":"1","From":"=?utf-8?q?Ilpo_J=C3=A4rvinen?= ","Date":"Fri, 10 Apr 2026 14:14:55 +0300 (EEST)","To":"=?iso-8859-2?q?Krzysztof_Wilczy=F1ski?= ","cc":"Bjorn Helgaas , Bjorn Helgaas ,\n Manivannan Sadhasivam ,\n Lorenzo Pieralisi ,\n Magnus Lindholm , Matt Turner ,\n Richard Henderson ,\n Christophe Leroy ,\n Madhavan Srinivasan ,\n Michael Ellerman , Nicholas Piggin ,\n Dexuan Cui ,\n =?iso-8859-2?q?Krzysztof_Ha=B3asa?= ,\n Lukas Wunner , Oliver O'Halloran ,\n Saurabh Singh Sengar ,\n Shuan He ,\n Srivatsa Bhat , linux-pci@vger.kernel.org,\n linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org","Subject":"Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()","In-Reply-To":"<20260410055040.39233-14-kwilczynski@kernel.org>","Message-ID":"<66eb23bf-1995-363f-78e6-f5a397a063a2@linux.intel.com>","References":"<20260410055040.39233-1-kwilczynski@kernel.org>\n <20260410055040.39233-14-kwilczynski@kernel.org>","X-Mailing-List":"linuxppc-dev@lists.ozlabs.org","List-Id":"","List-Help":"","List-Owner":"","List-Post":"","List-Archive":",\n ","List-Subscribe":",\n ,\n ","List-Unsubscribe":"","Precedence":"list","MIME-Version":"1.0","Content-Type":"multipart/mixed; boundary=\"8323328-133140870-1775819695=:1195\"","X-Spam-Status":"No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,\n\tDKIM_VALID,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS autolearn=disabled\n\tversion=4.0.1 OzLabs 8","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org"}},{"id":3675829,"web_url":"http://patchwork.ozlabs.org/comment/3675829/","msgid":"<20260410112132.GA1756033@rocinante>","date":"2026-04-10T11:21:32","subject":"Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()","submitter":{"id":86709,"url":"http://patchwork.ozlabs.org/api/people/86709/","name":"Krzysztof Wilczyński","email":"kwilczynski@kernel.org"},"content":"Hello,\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> > Also, remove the WARN() that fires when userspace attempts to\n> > mmap beyond the BAR bounds. The check still returns 0 to reject\n> > the mapping, but the warning is excessive for normal operation.\n> > \n> > A similar warning was removed from the PCI core in the commit\n> > 3b519e4ea618 (\"PCI: fix size checks for mmap() on /proc/bus/pci files\").\n> \n> This looks like entirely separate two changes to me which just happen \n> within the same context.\n\nTrue. I could split this into two separate patches. However, the early\nreturn is so trivial, that I decided to keep it here, in lieu of that the\nlinked patch did, too.\n\nThoughts?\n\nThank you!\n\n\tKrzysztof","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=aNkWsMkv;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=2404:9400:21b9:f100::1; helo=lists.ozlabs.org;\n envelope-from=linuxppc-dev+bounces-19563-incoming=patchwork.ozlabs.org@lists.ozlabs.org;\n receiver=patchwork.ozlabs.org)","lists.ozlabs.org;\n arc=none smtp.remote-ip=172.105.4.254","lists.ozlabs.org;\n dmarc=pass (p=quarantine dis=none) header.from=kernel.org","lists.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=aNkWsMkv;\n\tdkim-atps=neutral","lists.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org\n (client-ip=172.105.4.254; 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charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<66eb23bf-1995-363f-78e6-f5a397a063a2@linux.intel.com>","X-Spam-Status":"No, score=-0.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,\n\tDKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS\n\tautolearn=disabled version=4.0.1 OzLabs 8","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org"}},{"id":3675839,"web_url":"http://patchwork.ozlabs.org/comment/3675839/","msgid":"","date":"2026-04-10T11:32:43","subject":"Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()","submitter":{"id":83553,"url":"http://patchwork.ozlabs.org/api/people/83553/","name":"Ilpo Järvinen","email":"ilpo.jarvinen@linux.intel.com"},"content":"On Fri, 10 Apr 2026, Krzysztof Wilczyński wrote:\n\n> Hello,\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> > > Also, remove the WARN() that fires when userspace attempts to\n> > > mmap beyond the BAR bounds. The check still returns 0 to reject\n> > > the mapping, but the warning is excessive for normal operation.\n> > > \n> > > A similar warning was removed from the PCI core in the commit\n> > > 3b519e4ea618 (\"PCI: fix size checks for mmap() on /proc/bus/pci files\").\n> > \n> > This looks like entirely separate two changes to me which just happen \n> > within the same context.\n> \n> True. I could split this into two separate patches. However, the early\n> return is so trivial, that I decided to keep it here, in lieu of that the\n> linked patch did, too.\n> \n> Thoughts?\n\nIt's not just adding the early return that would go to the first patch but \nyou also need to rearrange the len for that. Effectively, the change is \nsplit in half, each becoming cleaner and more focused (both diff and the \nchangelog text).\n\nAs is I'm left on the borderline, while I can see it's \"correct\" after \nsplitting those changes inside my head, I also know it could have been \ndone better. I'd easily given rev-by for both if they'd have been done \nindividually, saved the time writing these emails about it, and \neffectively \"forgotten\" the patches (including upcoming versions of the \nseries).","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.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=TTWLZtYl;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=2404:9400:21b9:f100::1; helo=lists.ozlabs.org;\n envelope-from=linuxppc-dev+bounces-19565-incoming=patchwork.ozlabs.org@lists.ozlabs.org;\n receiver=patchwork.ozlabs.org)","lists.ozlabs.org; arc=none smtp.remote-ip=198.175.65.9","lists.ozlabs.org;\n dmarc=pass (p=none dis=none) header.from=linux.intel.com","lists.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=TTWLZtYl;\n\tdkim-atps=neutral","lists.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=linux.intel.com\n (client-ip=198.175.65.9; 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a=\"99472917\"","E=Sophos;i=\"6.23,171,1770624000\";\n d=\"scan'208\";a=\"99472917\"","E=Sophos;i=\"6.23,171,1770624000\";\n d=\"scan'208\";a=\"228225436\""],"X-ExtLoop1":"1","From":"=?utf-8?q?Ilpo_J=C3=A4rvinen?= ","Date":"Fri, 10 Apr 2026 14:32:43 +0300 (EEST)","To":"=?iso-8859-2?q?Krzysztof_Wilczy=F1ski?= ","cc":"Bjorn Helgaas , Bjorn Helgaas ,\n Manivannan Sadhasivam ,\n Lorenzo Pieralisi ,\n Magnus Lindholm , Matt Turner ,\n Richard Henderson ,\n Christophe Leroy ,\n Madhavan Srinivasan ,\n Michael Ellerman , Nicholas Piggin ,\n Dexuan Cui ,\n =?iso-8859-2?q?Krzysztof_Ha=B3asa?= ,\n Lukas Wunner , Oliver O'Halloran ,\n Saurabh Singh Sengar ,\n Shuan He ,\n Srivatsa Bhat , linux-pci@vger.kernel.org,\n linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org","Subject":"Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()","In-Reply-To":"<20260410112132.GA1756033@rocinante>","Message-ID":"","References":"<20260410055040.39233-1-kwilczynski@kernel.org>\n <20260410055040.39233-14-kwilczynski@kernel.org>\n <66eb23bf-1995-363f-78e6-f5a397a063a2@linux.intel.com>\n <20260410112132.GA1756033@rocinante>","X-Mailing-List":"linuxppc-dev@lists.ozlabs.org","List-Id":"","List-Help":"","List-Owner":"","List-Post":"","List-Archive":",\n ","List-Subscribe":",\n ,\n ","List-Unsubscribe":"","Precedence":"list","MIME-Version":"1.0","Content-Type":"multipart/mixed; BOUNDARY=\"8323328-135863821-1775820198=:1195\"","Content-ID":"<35660afc-f9b7-2ff0-7765-d108aab98c34@linux.intel.com>","X-Spam-Status":"No, score=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,\n\tDKIM_VALID,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS autolearn=disabled\n\tversion=4.0.1 OzLabs 8","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org"}},{"id":3675850,"web_url":"http://patchwork.ozlabs.org/comment/3675850/","msgid":"<20260410115541.GA1770099@rocinante>","date":"2026-04-10T11:55:41","subject":"Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()","submitter":{"id":86709,"url":"http://patchwork.ozlabs.org/api/people/86709/","name":"Krzysztof Wilczyński","email":"kwilczynski@kernel.org"},"content":"Hello,\n\n> > > This looks like entirely separate two changes to me which just happen \n> > > within the same context.\n> > \n> > True. I could split this into two separate patches. However, the early\n> > return is so trivial, that I decided to keep it here, in lieu of that the\n> > linked patch did, too.\n> > \n> > Thoughts?\n> \n> It's not just adding the early return that would go to the first patch but \n> you also need to rearrange the len for that. Effectively, the change is \n> split in half, each becoming cleaner and more focused (both diff and the \n> changelog text).\n> \n> As is I'm left on the borderline, while I can see it's \"correct\" after \n> splitting those changes inside my head, I also know it could have been \n> done better. I'd easily given rev-by for both if they'd have been done \n> individually, saved the time writing these emails about it, and \n> effectively \"forgotten\" the patches (including upcoming versions of the \n> series).\n\nA simple \"yes, please split\" would suffice. :) For future reference.\n\nThank you!\n\n\tKrzysztof","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=Lb/ZmOTV;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=2404:9400:21b9:f100::1; helo=lists.ozlabs.org;\n envelope-from=linuxppc-dev+bounces-19568-incoming=patchwork.ozlabs.org@lists.ozlabs.org;\n receiver=patchwork.ozlabs.org)","lists.ozlabs.org;\n arc=none smtp.remote-ip=\"2600:3c04:e001:324:0:1991:8:25\"","lists.ozlabs.org;\n dmarc=pass (p=quarantine dis=none) header.from=kernel.org","lists.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=Lb/ZmOTV;\n\tdkim-atps=neutral","lists.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org\n (client-ip=2600:3c04:e001:324:0:1991:8:25; 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