From patchwork Thu Nov 29 05:55:32 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sasha Levin X-Patchwork-Id: 10703939 X-Patchwork-Delegate: jikos@jikos.cz Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3404513A4 for ; Thu, 29 Nov 2018 05:59:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 275922E6A0 for ; Thu, 29 Nov 2018 05:59:27 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 191F72E6A9; Thu, 29 Nov 2018 05:59:27 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B68422E6A0 for ; Thu, 29 Nov 2018 05:59:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728832AbeK2RDe (ORCPT ); Thu, 29 Nov 2018 12:03:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:37806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727402AbeK2RDe (ORCPT ); Thu, 29 Nov 2018 12:03:34 -0500 Received: from sasha-vm.mshome.net (unknown [37.142.5.207]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DC95D208E7; Thu, 29 Nov 2018 05:59:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543471163; bh=USgoQ4D9VCbfZVSzN36RiwJFaTW0Xd3TaUs21r/PocE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T8Acej/vQ9KByqaO7/VIbLbBf7iwVu+rxQe0a3fZdPxKYrKpu8XWvAHoyi7TeqqgZ sOuPvs02PIeL4RzWcrb2VA+PC5pm3OR0e6xfu/LGq7e7jgFGVDuDNQeWh6jFHYaV28 7yqpCHNNnCzcvjH9Q6F3kKKS3a0xdmBsVMKygF+U= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: David Herrmann , Jiri Kosina , Sasha Levin , linux-input@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 41/68] Revert "HID: uhid: use strlcpy() instead of strncpy()" Date: Thu, 29 Nov 2018 00:55:32 -0500 Message-Id: <20181129055559.159228-41-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181129055559.159228-1-sashal@kernel.org> References: <20181129055559.159228-1-sashal@kernel.org> Sender: linux-input-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: David Herrmann [ Upstream commit 4d26d1d1e8065bb3326a7c06d5d4698e581443a9 ] This reverts commit 336fd4f5f25157e9e8bd50e898a1bbcd99eaea46. Please note that `strlcpy()` does *NOT* do what you think it does. strlcpy() *ALWAYS* reads the full input string, regardless of the 'length' parameter. That is, if the input is not zero-terminated, strlcpy() will *READ* beyond input boundaries. It does this, because it always returns the size it *would* copy if the target was big enough, not the truncated size it actually copied. The original code was perfectly fine. The hid device is zero-initialized and the strncpy() functions copied up to n-1 characters. The result is always zero-terminated this way. This is the third time someone tried to replace strncpy with strlcpy in this function, and gets it wrong. I now added a comment that should at least make people reconsider. Signed-off-by: David Herrmann Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin --- drivers/hid/uhid.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c index 051639c09f72..840634e0f1e3 100644 --- a/drivers/hid/uhid.c +++ b/drivers/hid/uhid.c @@ -497,12 +497,13 @@ static int uhid_dev_create2(struct uhid_device *uhid, goto err_free; } - len = min(sizeof(hid->name), sizeof(ev->u.create2.name)); - strlcpy(hid->name, ev->u.create2.name, len); - len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)); - strlcpy(hid->phys, ev->u.create2.phys, len); - len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)); - strlcpy(hid->uniq, ev->u.create2.uniq, len); + /* @hid is zero-initialized, strncpy() is correct, strlcpy() not */ + len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1; + strncpy(hid->name, ev->u.create2.name, len); + len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1; + strncpy(hid->phys, ev->u.create2.phys, len); + len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1; + strncpy(hid->uniq, ev->u.create2.uniq, len); hid->ll_driver = &uhid_hid_driver; hid->bus = ev->u.create2.bus;