From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 DF9CDC433E0 for ; Sat, 20 Jun 2020 15:05:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C625D207DD for ; Sat, 20 Jun 2020 15:05:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728336AbgFTPFk (ORCPT ); Sat, 20 Jun 2020 11:05:40 -0400 Received: from mail-lj1-f193.google.com ([209.85.208.193]:39429 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728226AbgFTPFj (ORCPT ); Sat, 20 Jun 2020 11:05:39 -0400 Received: by mail-lj1-f193.google.com with SMTP id a9so14689834ljn.6 for ; Sat, 20 Jun 2020 08:05:37 -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:mime-version :content-transfer-encoding; bh=AbdOzdHlWKQ2A53AC9U9xzo8udqOk2K2fGGjIVcMgws=; b=SQok47lO51Rup7rtvWC9Q5fMLrzwQhmkTqWWQKP6sGxa6tLpvxKf9nQLExR7Yegy6L j+W0BlAatQ0NkSq8KE0NNDy4h1i1HcOLOjVXpi+04VdUZmV7DFoMqhLUccIXmodVeWWR cZpfu/NJoQ3XW1nNez+nUVOLuyVbFEIh23uPddLI5+6g9G0UquA/VlmMXO7bncsyC7kP aK4JGzAJDrhuIsKvaesrWV05tEbkfg+Q3BCKjVFS0jLjvXWsWpMp3BXzQQEiWv3N5GIy SwOs1wpINKEBZ46ZDk6baxlApzA6DO1z5RzoLNEEoGLrPTxwJwBLkNUZTVmRsbtcYp1T /Bng== X-Gm-Message-State: AOAM530pEXjggeOwTFkXiRRwyHn2w2v9/v4Y7FZKMgugV/QXZtZx0K7n W2F2zccZkIbhmqDnPJW8EnMzLx+RLjjRKw== X-Google-Smtp-Source: ABdhPJyMxDjxla5jDylaP2ys+kG8FYZz/1U4aHCzjUkq6lGx47llrQKTrzsRB76ovI9U9LZsbwFNAQ== X-Received: by 2002:a2e:9586:: with SMTP id w6mr4075012ljh.318.1592665537268; Sat, 20 Jun 2020 08:05:37 -0700 (PDT) Received: from localhost.localdomain ([213.87.137.195]) by smtp.googlemail.com with ESMTPSA id u8sm2127832lff.38.2020.06.20.08.05.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 20 Jun 2020 08:05:36 -0700 (PDT) From: Denis Efremov To: Greg Kroah-Hartman , "Rafael J. Wysocki" Cc: Denis Efremov , linux-kernel@vger.kernel.org Subject: [PATCH] driver core: Use scnprintf() instead of snprintf() in device show functions Date: Sat, 20 Jun 2020 18:05:29 +0300 Message-Id: <20200620150529.18678-1-efremov@linux.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >From Documentation/filesystems/sysfs.txt: - show() must not use snprintf() when formatting the value to be returned to user space. If you can guarantee that an overflow will never happen you can use sprintf() otherwise you must use scnprintf(). The reason is that snprintf() returns the length the resulting string would be, assuming the data will fit into the destination array. scnprintf() returns the length of the string actually created in buf. device_show_{ulong,int,bool}() functions are reference implementation and should respect the kernel documentation. Signed-off-by: Denis Efremov --- Actually, I don't know why snprintf() is used here initially. It looks safe to use sprintf(). drivers/base/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 67d39a90b45c..2815deb511fc 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1472,7 +1472,7 @@ ssize_t device_show_ulong(struct device *dev, char *buf) { struct dev_ext_attribute *ea = to_ext_attr(attr); - return snprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var)); + return scnprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var)); } EXPORT_SYMBOL_GPL(device_show_ulong); @@ -1502,7 +1502,7 @@ ssize_t device_show_int(struct device *dev, { struct dev_ext_attribute *ea = to_ext_attr(attr); - return snprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var)); + return scnprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var)); } EXPORT_SYMBOL_GPL(device_show_int); @@ -1523,7 +1523,7 @@ ssize_t device_show_bool(struct device *dev, struct device_attribute *attr, { struct dev_ext_attribute *ea = to_ext_attr(attr); - return snprintf(buf, PAGE_SIZE, "%d\n", *(bool *)(ea->var)); + return scnprintf(buf, PAGE_SIZE, "%d\n", *(bool *)(ea->var)); } EXPORT_SYMBOL_GPL(device_show_bool); -- 2.26.2