From patchwork Mon Sep 25 04:31:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Justin Stitt X-Patchwork-Id: 727465 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CC20CE7A89 for ; Mon, 25 Sep 2023 04:31:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229504AbjIYEbU (ORCPT ); Mon, 25 Sep 2023 00:31:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229460AbjIYEbT (ORCPT ); Mon, 25 Sep 2023 00:31:19 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1993ADF for ; Sun, 24 Sep 2023 21:31:09 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-59ee66806d7so99629897b3.0 for ; Sun, 24 Sep 2023 21:31:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695616268; x=1696221068; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=u9uHumzTyf+gjmcuSq47+yVY/ogRXox3AvMpCppjL8A=; b=L/5s9hS+tgCT2x3dMNT6z9FXQPlt6oZJn2ctzmnys3Nubs7O+NOlwJvHa0NqJMz7co QLeQbpZgRyXETyg1V7rJqQLAkqv/g6YJgs0u2g+XY1WGuo7zu1g5U9KHfgeg9kyEoZ7L /O1KPPNFAPH+RUk3mM5VppU1WixW2VRqla5TK1A8F34YyEj8ykzAJtl8A4fRyuln4uCI 302kH3kfDLsi9ZNMdR94zUOskb4Bk7kfi5eA95zgoRZpQBO58QVsDHQ8jB09J/qNB+9m bm6jQd/6j6qQ09o8zw1AtmLzxk/1DWpcjbUMhIasHxfzHxfDQmSKyh7okAk7KVIiGOqS 5Rnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695616268; x=1696221068; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=u9uHumzTyf+gjmcuSq47+yVY/ogRXox3AvMpCppjL8A=; b=FReSJ/Nt93f/0aI8cB/qxnqdqmgCTE0VCrxTIneH5O0o3mqH39R9OdV4s6nkf3kG7r vrwZnyqr+eg8I5XaVhce1B5cou6KUcLSAmXIzMGqHkSJskD2sMrXG4qk9JRhekInJk2n o2QqWjfiflqYSttB5QCIlldfCIHsQXPh+PFS6BGMrk2tC3YuBOdFlYZ4mYkVi7tuDmiE ypYR19jegdj1wXhe5zt0/MxoN0kO2tzZAwnq+kUN52rcJjmlApPz1TUcKENVUa3eKrjd +IWhmkFmQvOBSNIgLL7hGuY8e72+ItzB5owGbOqpcYaS0qDLoKBehjQGxnis9/ACnqH/ sZJg== X-Gm-Message-State: AOJu0YxdbRT/YAjr+9YJk3UZa2zG3Tvxb/rKb4MLfnQMQfQhvEkYHPPr 97CkxLVqG1WZyZhQ7oOoZirOMuDrK0SiPo+bJg== X-Google-Smtp-Source: AGHT+IHPf37TtcAQw/kZ/if+wxjiRYYEoKTZ/EE11hWMdLINb9IuxCcKQ3MtEWuw4p0np8qDJEFrJ0n1xqFOgQcaNA== X-Received: from jstitt-linux1.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:23b5]) (user=justinstitt job=sendgmr) by 2002:a81:eb0c:0:b0:58c:7cb1:10f with SMTP id n12-20020a81eb0c000000b0058c7cb1010fmr64056ywm.9.1695616268339; Sun, 24 Sep 2023 21:31:08 -0700 (PDT) Date: Mon, 25 Sep 2023 04:31:05 +0000 Mime-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAAgNEWUC/5XNSw6DIBSF4a0Yxr0NoK2PUffROFC86E0rELBEY 9x7qTvo8D+D8+0soCcMrMl25jFSIGtSyEvG1NSZEYGG1ExymfNaCgiLN8ptMHiK6AOQcZ8FZgo KutVJvoLDFyjIVVHyqpZF3w8svTmPmtZTerapJwqL9dsJR/Fb/zeiAAG61HdddDelK/EYrR3fe FV2Zu1xHF9KMXl23wAAAA== X-Developer-Key: i=justinstitt@google.com; a=ed25519; pk=tC3hNkJQTpNX/gLKxTNQKDmiQl6QjBNCGKJINqAdJsE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1695616267; l=2212; i=justinstitt@google.com; s=20230717; h=from:subject:message-id; bh=Sw+ZJKnGZ+JwKov1VeH3ACtZRgGvZ2w/x0E7T3CskvA=; b=DqRU49YR3wzheuEpQc3E2ii9tcBqhXWtzvAnZX/mi6knIBj7UivaiZux27mnaODzfuwNsJ4jT 6pgb6ayjgqFBTY47ZtK16xtYWzLYXRTlLuAQyXIH0qqWIODFqN7j+W7 X-Mailer: b4 0.12.3 Message-ID: <20230925-strncpy-drivers-input-misc-axp20x-pek-c-v2-1-ff7abe8498d6@google.com> Subject: [PATCH v2] Input: axp20x-pek - avoid needless newline removal From: Justin Stitt To: Dmitry Torokhov , Chen-Yu Tsai Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Kees Cook , Justin Stitt Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org This code is doing more work than it needs to. Before handing off `val_str` to `kstrtouint()` we are eagerly removing any trailing newline which requires copying `buf`, validating it's length and checking/replacing any potential newlines. kstrtouint() handles this implicitly: kstrtouint -> kstrotoull -> (documentation) | /** | * kstrtoull - convert a string to an unsigned long long | * @s: The start of the string. The string must be null-terminated, and may also | * include a single newline before its terminating null. The first character | ... Let's remove the redundant functionality and let kstrtouint handle it. Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Suggested-by: Kees Cook Signed-off-by: Justin Stitt --- Changes in v2: - remove eager newline removal (thanks Kees) - use better subject line (thanks Kees) - rebase on 6465e260f4879080 - Link to v1: https://lore.kernel.org/r/20230921-strncpy-drivers-input-misc-axp20x-pek-c-v1-1-f7f6f4a5cf81@google.com --- Note: build-tested only. --- drivers/input/misc/axp20x-pek.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) --- base-commit: 6465e260f48790807eef06b583b38ca9789b6072 change-id: 20230921-strncpy-drivers-input-misc-axp20x-pek-c-3c4708924bbd Best regards, -- Justin Stitt diff --git a/drivers/input/misc/axp20x-pek.c b/drivers/input/misc/axp20x-pek.c index 4581606a28d6..24f9e9d893de 100644 --- a/drivers/input/misc/axp20x-pek.c +++ b/drivers/input/misc/axp20x-pek.c @@ -133,20 +133,11 @@ static ssize_t axp20x_store_attr(struct device *dev, size_t count) { struct axp20x_pek *axp20x_pek = dev_get_drvdata(dev); - char val_str[20]; - size_t len; int ret, i; unsigned int val, idx = 0; unsigned int best_err = UINT_MAX; - val_str[sizeof(val_str) - 1] = '\0'; - strncpy(val_str, buf, sizeof(val_str) - 1); - len = strlen(val_str); - - if (len && val_str[len - 1] == '\n') - val_str[len - 1] = '\0'; - - ret = kstrtouint(val_str, 10, &val); + ret = kstrtouint(buf, 10, &val); if (ret) return ret;