From patchwork Fri Jun 4 13:32:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= X-Patchwork-Id: 12299759 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C6E2C07E94 for ; Fri, 4 Jun 2021 13:32:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E594E613FE for ; Fri, 4 Jun 2021 13:32:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230282AbhFDNeg (ORCPT ); Fri, 4 Jun 2021 09:34:36 -0400 Received: from mail-qk1-f176.google.com ([209.85.222.176]:34402 "EHLO mail-qk1-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230122AbhFDNef (ORCPT ); Fri, 4 Jun 2021 09:34:35 -0400 Received: by mail-qk1-f176.google.com with SMTP id k11so7648242qkk.1 for ; Fri, 04 Jun 2021 06:32:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=zA3/cfdzVIr5cLh/J+wg9gDOYGj6S6m5ZJD71R+yPk4=; b=QV1DBlfPSuBi7PYdWjytjArbkBrMojbPdTYRqwQhI8zaMowCyIwQjgXsAftiPpkQgH QUlfpzaYHiwnVMgD8M8t1kI290rRXwoMv2QRJAZT7JipMZsyfipOt2HSG3EbIs2ZBcAf KY1kVZX8pzlR34V4quGGUxbGFEkHcnlKSM21KAU8aj9dUq/oakaEGBj6Nfuu/7Pql7KX UbZ+ui10pWlkAjLvwPzuuhAxMZKKGfVd/iiH9h9i6TF1LcStFuLDwWirnDUe29O4APzs gIruCrigD0JITXK2IjUSWRuD/fabI01TPHHFZ8R+tJu18GjP9uFLMt0QyaOa4EwE/PjY HYRg== X-Gm-Message-State: AOAM533pXL3iYfMy+DPPw60sAWwG0QbRRwKjalCaFWVhhYGifDlLOJxh /0b1tlBwXTg61dBRzdvy7t0= X-Google-Smtp-Source: ABdhPJyIM0cfKjUEdW2OkwQ9ncmanXPqTrSoJWo1H6K6CtRDy7i5ZUIPyVf61zsfzgrbvcH1pRE0NA== X-Received: by 2002:a05:620a:b1b:: with SMTP id t27mr4331322qkg.42.1622813568937; Fri, 04 Jun 2021 06:32:48 -0700 (PDT) Received: from workstation.lan ([95.155.85.46]) by smtp.gmail.com with ESMTPSA id b189sm3965912qkc.91.2021.06.04.06.32.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jun 2021 06:32:48 -0700 (PDT) From: =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= To: Bjorn Helgaas Cc: Logan Gunthorpe , Joe Perches , "Oliver O'Halloran" , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Tyrel Datwyler , Russell Currey , Kurt Schwemmer , Vidya Sagar , Xiongfeng Wang , linux-pci@vger.kernel.org Subject: [PATCH v7 6/6] PCI/sysfs: Fix a buffer overrun problem with dsm_label_utf16s_to_utf8s() Date: Fri, 4 Jun 2021 13:32:30 +0000 Message-Id: <20210604133230.983956-7-kw@linux.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210604133230.983956-1-kw@linux.com> References: <20210604133230.983956-1-kw@linux.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org When using ACPI to retrieve a device label from _DSM using the dsm_get_label() function the result can be retrieved either as a string value or a pointer to a buffer. Should it be the latter, then an additional function called dsm_label_utf16s_to_utf8s() will be invoked to convert any UTF16 characters to UTF8 so that the value could be safely stored and later displayed through a relevant sysfs object. Internally, dsm_label_utf16s_to_utf8s() calls the utf16s_to_utf8s() function to handle the conversion setting the limit of the data that can be saved into a provided buffer as a result of the character conversion to be a total of PAGE_SIZE. The utf16s_to_utf8s() function returns an integer value denoting the number of bytes that have been written into the provided buffer. Following the execution of the utf16s_to_utf8s() a newline character will be added at the end of the resulting buffer so that when the value is read in the userspace through the sysfs object then it would include newline making it more accessible when working with the sysfs file system in the shell, etc. Normally, this wouldn't be a problem, but if the function utf16s_to_utf8s() happens to return the number of bytes written to be precisely PAGE_SIZE, then we would overrun the buffer and write the newline character outside the allotted space which can have undefined consequences or result in a failure. To fix this buffer overrun, ensure that there always is enough space left for the newline character to be safely appended. Fixes: 6058989bad05 ("PCI: Export ACPI _DSM provided firmware instance number and string name to sysfs") Reported-by: Joe Perches Signed-off-by: Krzysztof Wilczyński --- drivers/pci/pci-label.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c index 000e169c7197..0c6446519640 100644 --- a/drivers/pci/pci-label.c +++ b/drivers/pci/pci-label.c @@ -146,8 +146,8 @@ static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf) len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer, obj->buffer.length, UTF16_LITTLE_ENDIAN, - buf, PAGE_SIZE); - buf[len] = '\n'; + buf, PAGE_SIZE - 1); + buf[len++] = '\n'; return len; }