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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7860C433EF for ; Mon, 15 Nov 2021 17:43:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D6DC6339B for ; Mon, 15 Nov 2021 17:43:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238218AbhKORqU (ORCPT ); Mon, 15 Nov 2021 12:46:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:48808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237392AbhKORTe (ORCPT ); Mon, 15 Nov 2021 12:19:34 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0C74C63243; Mon, 15 Nov 2021 17:14:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636996481; bh=dNrSxTnoCVLLjsQAZc8rgxLxELIajzBjpIq6pIbRNM4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H+cC9sPdloX6nXbgOCSlrfX7YpV8OVsWd0+iG2zyJVMK1rtRCJJfgfrD1KtV2D/Tv 5ynAryyFwSewHuVjqBy29ISRMfMz9vYeNQh0epZcHr6Soo6nf3RxoDX5yBnQI6PNV1 Ad6BCUwRpqTu115HNKSsP2uyaz7W/E1BU7C22apI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lasse Collin , Gao Xiang , Sasha Levin Subject: [PATCH 5.4 155/355] lib/xz: Validate the value before assigning it to an enum variable Date: Mon, 15 Nov 2021 18:01:19 +0100 Message-Id: <20211115165318.802231777@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165313.549179499@linuxfoundation.org> References: <20211115165313.549179499@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lasse Collin [ Upstream commit 4f8d7abaa413c34da9d751289849dbfb7c977d05 ] This might matter, for example, if the underlying type of enum xz_check was a signed char. In such a case the validation wouldn't have caught an unsupported header. I don't know if this problem can occur in the kernel on any arch but it's still good to fix it because some people might copy the XZ code to their own projects from Linux instead of the upstream XZ Embedded repository. This change may increase the code size by a few bytes. An alternative would have been to use an unsigned int instead of enum xz_check but using an enumeration looks cleaner. Link: https://lore.kernel.org/r/20211010213145.17462-3-xiang@kernel.org Signed-off-by: Lasse Collin Signed-off-by: Gao Xiang Signed-off-by: Sasha Levin --- lib/xz/xz_dec_stream.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/lib/xz/xz_dec_stream.c b/lib/xz/xz_dec_stream.c index bd1d182419d7e..0b161f90d8d80 100644 --- a/lib/xz/xz_dec_stream.c +++ b/lib/xz/xz_dec_stream.c @@ -402,12 +402,12 @@ static enum xz_ret dec_stream_header(struct xz_dec *s) * we will accept other check types too, but then the check won't * be verified and a warning (XZ_UNSUPPORTED_CHECK) will be given. */ + if (s->temp.buf[HEADER_MAGIC_SIZE + 1] > XZ_CHECK_MAX) + return XZ_OPTIONS_ERROR; + s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1]; #ifdef XZ_DEC_ANY_CHECK - if (s->check_type > XZ_CHECK_MAX) - return XZ_OPTIONS_ERROR; - if (s->check_type > XZ_CHECK_CRC32) return XZ_UNSUPPORTED_CHECK; #else -- 2.33.0