From nobody Wed Sep 3 06:43:54 2025 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 609B2ECAAA1 for ; Mon, 24 Oct 2022 12:36:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231349AbiJXMgM (ORCPT ); Mon, 24 Oct 2022 08:36:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234323AbiJXMaB (ORCPT ); Mon, 24 Oct 2022 08:30:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 545A2356EA; Mon, 24 Oct 2022 05:04:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8719361295; Mon, 24 Oct 2022 12:03:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97DDEC433C1; Mon, 24 Oct 2022 12:03:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666613038; bh=c9KwSiNVgBXBuKA/mG8YVGWL/opA9IdLJkp3LRCodbs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YbdfvEj2ScSh0UmzMbT1QJW7K6CYLcMSa0fKiiFBbkyzMU1tbZiO8Xqt64YeUyBKz Igf9Af0s5Iqb/bkXdMhOWIFo1HarNc+rD93h6zF3+iBNV+CW4DV9CnTPtnNNM9484h MohChdSypAjREgukUwIcX3ExhvFHDQYD9iGEC9cM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hyunwoo Kim , Jiri Kosina , Sasha Levin Subject: [PATCH 4.19 213/229] HID: roccat: Fix use-after-free in roccat_read() Date: Mon, 24 Oct 2022 13:32:12 +0200 Message-Id: <20221024113006.104138122@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024112959.085534368@linuxfoundation.org> References: <20221024112959.085534368@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Hyunwoo Kim [ Upstream commit cacdb14b1c8d3804a3a7d31773bc7569837b71a4 ] roccat_report_event() is responsible for registering roccat-related reports in struct roccat_device. int roccat_report_event(int minor, u8 const *data) { struct roccat_device *device; struct roccat_reader *reader; struct roccat_report *report; uint8_t *new_value; device =3D devices[minor]; new_value =3D kmemdup(data, device->report_size, GFP_ATOMIC); if (!new_value) return -ENOMEM; report =3D &device->cbuf[device->cbuf_end]; /* passing NULL is safe */ kfree(report->value); ... The registered report is stored in the struct roccat_device member "struct roccat_report cbuf[ROCCAT_CBUF_SIZE];". If more reports are received than the "ROCCAT_CBUF_SIZE" value, kfree() the saved report from cbuf[0] and allocates a new reprot. Since there is no lock when this kfree() is performed, kfree() can be performed even while reading the saved report. static ssize_t roccat_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct roccat_reader *reader =3D file->private_data; struct roccat_device *device =3D reader->device; struct roccat_report *report; ssize_t retval =3D 0, len; DECLARE_WAITQUEUE(wait, current); mutex_lock(&device->cbuf_lock); ... report =3D &device->cbuf[reader->cbuf_start]; /* * If report is larger than requested amount of data, rest of report * is lost! */ len =3D device->report_size > count ? count : device->report_size; if (copy_to_user(buffer, report->value, len)) { retval =3D -EFAULT; goto exit_unlock; } ... The roccat_read() function receives the device->cbuf report and delivers it to the user through copy_to_user(). If the N+ROCCAT_CBUF_SIZE th report is received while copying of the Nth report->value is in progress, the pointer that copy_to_user() is working on is kfree()ed and UAF read may occur. (race condition) Since the device node of this driver does not set separate permissions, this is not a security vulnerability, but because it is used for requesting screen display of profile or dpi settings, a user using the roccat device can apply udev to this device node or There is a possibility to use it by giving. Signed-off-by: Hyunwoo Kim Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin --- drivers/hid/hid-roccat.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/hid/hid-roccat.c b/drivers/hid/hid-roccat.c index 5be8de70c651..c9cec00b4e6e 100644 --- a/drivers/hid/hid-roccat.c +++ b/drivers/hid/hid-roccat.c @@ -260,6 +260,8 @@ int roccat_report_event(int minor, u8 const *data) if (!new_value) return -ENOMEM; =20 + mutex_lock(&device->cbuf_lock); + report =3D &device->cbuf[device->cbuf_end]; =20 /* passing NULL is safe */ @@ -279,6 +281,8 @@ int roccat_report_event(int minor, u8 const *data) reader->cbuf_start =3D (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE; } =20 + mutex_unlock(&device->cbuf_lock); + wake_up_interruptible(&device->wait); return 0; } --=20 2.35.1