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Fri, 10 Apr 2026 05:51:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775800291; bh=Nh7a1ArkRQeNDsZQ4G4s7B27zHMA9oeNqUUdRhEq7Fs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XGDauH65tg4bJ9ruSw7Z6gY2FgZvSRdoiVLxHgO6FHnL6maslO7dpOby3VlujfHY6 lp71qjGPI9FnJ+YkDygQZLF5ftlEhT8uDDo3MIf7YZBN6Itnjwxnhzm72KF4k+HFD0 GpQmeT9QHiDMxTrn+nKdUqMsIwo+qI9jQVMvVAYuN333KZPyYMJovH9pMhkBeIGf2V 5iyGh6zq4JQKEamShug3eT7CotSXt3MqJ+1Tg0qxcotMGh+oKGvTXX7Cs6ugCuVz52 aLYqZNvCXjb5KJX1U93HTRBGcVdyqotqEjICJRYp1s9beAn1C1ORBRpyLbEfda9fm/ Li3fkgG20rMiw== From: =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= To: Bjorn Helgaas Cc: Bjorn Helgaas , Manivannan Sadhasivam , Lorenzo Pieralisi , Magnus Lindholm , Matt Turner , Richard Henderson , Christophe Leroy , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Dexuan Cui , =?UTF-8?q?Krzysztof=20Ha=C5=82asa?= , Lukas Wunner , "Oliver O'Halloran" , Saurabh Singh Sengar , Shuan He , Srivatsa Bhat , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , linux-pci@vger.kernel.org, linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits() Date: Fri, 10 Apr 2026 05:50:33 +0000 Message-ID: <20260410055040.39233-14-kwilczynski@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260410055040.39233-1-kwilczynski@kernel.org> References: <20260410055040.39233-1-kwilczynski@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. Thus, add an early return for empty resources. Also, remove the WARN() that fires when userspace attempts to mmap beyond the BAR bounds. The check still returns 0 to reject the mapping, but the warning is excessive for normal operation. A similar warning was removed from the PCI core in the commit 3b519e4ea618 ("PCI: fix size checks for mmap() on /proc/bus/pci files"). Signed-off-by: Krzysztof Wilczyński --- arch/alpha/kernel/pci-sysfs.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c index 7aac5e76dcd6..867199b988de 100644 --- a/arch/alpha/kernel/pci-sysfs.c +++ b/arch/alpha/kernel/pci-sysfs.c @@ -37,20 +37,18 @@ 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; - WARN(1, "process \"%s\" tried to map%s 0x%08lx-0x%08lx on %s BAR %d " - "(size 0x%08lx)\n", - current->comm, sparse ? " sparse" : "", start, start + nr, - pci_name(pdev), num, size); - return 0; + return start < size && size - start >= nr; } /** -- 2.53.0