From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B410341DED4 for ; Wed, 29 Jul 2026 07:54:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785311661; cv=none; b=dqAyIrE5XaBGDZWcSNNuc4tiCRX0gaIYQexq0BkMGgRJ1Xh5uaXVpR23SivHwqwEW8VGzvG1Cuy4E/KLvX2CRDNVk8klj2TNigLNjhA8RzqQk3FCHGItod7HALUyK3TGG7Ds+c321yqLj3Cbigu7vEnxHUJY989eZw2P7qNwcPQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785311661; c=relaxed/simple; bh=VCVA2PidKO0ADO09XqBQEx9Ld/BHny/owjsuV9okZu4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=rzxxANNGnnbLKYMSFyMMmvwGt3YsnbDg1Xt06Oy96n9X1imD6sckx1CxUrlt4zSWU8GwbHYHaFNnPnRR7wdFSueVDCpPB+tInC9YyaJTIncKgGO115JrhVZROkItkaCLHKTftxwtN5726ngexrsQxQgvYfFRlPNc/ADcmY+R+yE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ymyo2Kns; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ymyo2Kns" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89EAB1F000E9; Wed, 29 Jul 2026 07:54:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785311656; bh=GxZ7QVVH5311f113ShfekrCsgA2DAihos3qOEtFj4RE=; h=From:To:Cc:Subject:Date; b=Ymyo2Kns3N4AdGmjypWe7ey9gP7WsaBcqmm37V2wVrrsJEGwMl+7uJUUQP6sQYqjm c0scQaQouUQos+g8DibUOK93wtPRU2lFbqZJenQAg45c1leGfloRQRPMidX5/fE+ZK JZ1XzIRQ88quy5H2os+e+F7X1Mqv877rpCTRH3aaUH8N9VJ2NhApc8yTis3SstOoIA K5Zo/ZHFztlCSPYbUcCVQJ+EzLsNs4qMNq9GLtbntvPQosDOe//8XWG5bJufRnrZIr LwwJQ1AfS9yse5pzPe8rxpVyZZyfgXQRM7v4UGJu89y0kqiaMwVQp+xbD7wvkdTuoH rfp6V2jIFh77Q== From: =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= To: Bjorn Helgaas Cc: Bjorn Helgaas , Manivannan Sadhasivam , Lorenzo Pieralisi , Ira Weiny , Kees Cook , linux-pci@vger.kernel.org Subject: [PATCH] PCI/proc: Warn on writes to kernel-exclusive config space regions Date: Wed, 29 Jul 2026 07:54:13 +0000 Message-ID: <20260729075413.1215821-1-kwilczynski@kernel.org> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, a driver can claim a region of a device's config space as exclusive using pci_request_config_region_exclusive(), after which a write to that region originating from user space is expected to emit a warning and taint the kernel. The check is advisory only, as the write itself is still allowed to proceed. Since commit 278294798ac9 ("PCI: Allow drivers to request exclusive config regions"), the sysfs config space attribute performs this check in pci_write_config(), but the procfs interface was never updated. A write performed through /proc/bus/pci/BB/DD.F therefore bypasses the detection entirely, even though both interfaces offer the same level of access. Thus, add the same resource_is_exclusive() check to proc_bus_pci_write(). Signed-off-by: Krzysztof Wilczyński --- drivers/pci/proc.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index 71ad289fcb8e..12200979d3a8 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -14,6 +14,8 @@ #include #include #include +#include +#include #include #include "pci.h" @@ -122,6 +124,12 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf, if (ret) return ret; + if (resource_is_exclusive(&dev->driver_exclusive_resource, pos, nbytes)) { + pci_warn_once(dev, "%s: Unexpected write to kernel-exclusive config offset %x", + current->comm, pos); + add_taint(TAINT_USER, LOCKDEP_STILL_OK); + } + if (pos >= size) return 0; if (nbytes >= size) -- 2.55.0