From patchwork Fri Aug 25 03:06:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 13364980 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 C559BC6FA8F for ; Fri, 25 Aug 2023 03:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229671AbjHYDF6 (ORCPT ); Thu, 24 Aug 2023 23:05:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234492AbjHYDFz (ORCPT ); Thu, 24 Aug 2023 23:05:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 983D1198E; Thu, 24 Aug 2023 20:05:53 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 372B56120E; Fri, 25 Aug 2023 03:05:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2A8DC433C8; Fri, 25 Aug 2023 03:05:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692932752; bh=0myg6Da5IOq3dGebwmAyZr2L0BX2BU7FwaZAc1bAE7U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Hwvz3MaWUO9uJUyeLAckuLsQTxs7tfsIu253YDaPNSkAjWf/KXx0Ky0iRPAkSCPdD Laccl6reWIGxBJFV6OupH/HShh9hChFDaW0zy7RWb8UDPb4xlSVl81f4kJJt+CUV7B uUy1QGfBjvKv/Z/M7zJ8PgpNGYoJS+jpKCiU0s01XfE2sjGgXIjMJ61Zts6M1duxOw DpoZjoVC+97Msuxi+F8VtmMf/vzdYije35GhJKB2JjK47/FiaUefFDOfe7oPJGHO3o zsCZHrPhWPhHfJdko0AL+y2zu4eMjfNL66BYe6UKmqpwbWglx8Utm0gOMtSC8huJPd hCRY9oxDqigZw== Date: Thu, 24 Aug 2023 21:06:51 -0600 From: "Gustavo A. R. Silva" To: Brian Norris , Kalle Valo , Amitkumar Karwar , Xinming Hu , Dan Williams Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" , linux-hardening@vger.kernel.org Subject: [PATCH v2 1/3] wifi: mwifiex: Fix tlv_buf_left calculation Message-ID: <06668edd68e7a26bbfeebd1201ae077a2a7a8bce.1692931954.git.gustavoars@kernel.org> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org In a TLV encoding scheme, the Length part represents the length after the header containing the values for type and length. In this case, `tlv_len` should be: tlv_len == (sizeof(*tlv_rxba) - 1) - sizeof(tlv_rxba->header) + tlv_bitmap_len Notice that the `- 1` accounts for the one-element array `bitmap`, which 1-byte size is already included in `sizeof(*tlv_rxba)`. So, if the above is correct, there is a double-counting of some members in `struct mwifiex_ie_types_rxba_sync`, when `tlv_buf_left` and `tmp` are calculated: 968 tlv_buf_left -= (sizeof(*tlv_rxba) + tlv_len); 969 tmp = (u8 *)tlv_rxba + tlv_len + sizeof(*tlv_rxba); in specific, members: drivers/net/wireless/marvell/mwifiex/fw.h:777 777 u8 mac[ETH_ALEN]; 778 u8 tid; 779 u8 reserved; 780 __le16 seq_num; 781 __le16 bitmap_len; This is clearly wrong, and affects the subsequent decoding of data in `event_buf` through `tlv_rxba`: 970 tlv_rxba = (struct mwifiex_ie_types_rxba_sync *)tmp; Fix this by using `sizeof(tlv_rxba->header)` instead of `sizeof(*tlv_rxba)` in the calculation of `tlv_buf_left` and `tmp`. This results in the following binary differences before/after changes: | drivers/net/wireless/marvell/mwifiex/11n_rxreorder.o | @@ -4698,11 +4698,11 @@ | drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c:968 | tlv_buf_left -= (sizeof(tlv_rxba->header) + tlv_len); | - 1da7: lea -0x11(%rbx),%edx | + 1da7: lea -0x4(%rbx),%edx | 1daa: movzwl %bp,%eax | drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c:969 | tmp = (u8 *)tlv_rxba + sizeof(tlv_rxba->header) + tlv_len; | - 1dad: lea 0x11(%r15,%rbp,1),%r15 | + 1dad: lea 0x4(%r15,%rbp,1),%r15 The above reflects the desired change: avoid counting 13 too many bytes; which is the total size of the double-counted members in `struct mwifiex_ie_types_rxba_sync`: $ pahole -C mwifiex_ie_types_rxba_sync drivers/net/wireless/marvell/mwifiex/11n_rxreorder.o struct mwifiex_ie_types_rxba_sync { struct mwifiex_ie_types_header header; /* 0 4 */ |----------------------------------------------------------------------- | u8 mac[6]; /* 4 6 */ | | u8 tid; /* 10 1 */ | | u8 reserved; /* 11 1 */ | | __le16 seq_num; /* 12 2 */ | | __le16 bitmap_len; /* 14 2 */ | | u8 bitmap[1]; /* 16 1 */ | |----------------------------------------------------------------------| | 13 bytes| ----------- /* size: 17, cachelines: 1, members: 7 */ /* last cacheline: 17 bytes */ } __attribute__((__packed__)); Fixes: 99ffe72cdae4 ("mwifiex: process rxba_sync event") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva Reviewed-by: Kees Cook --- Changes in v2: - Fix typo in changelog text: s/too bytes/too many bytes - Update binary diff snapshot in changelog text. v1: - Link: https://lore.kernel.org/linux-hardening/698dc480d939e3ae490140db5c2f36eb84093594.1692829410.git.gustavoars@kernel.org/ drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c index 391793a16adc..d1d3632a3ed7 100644 --- a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c +++ b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c @@ -965,8 +965,8 @@ void mwifiex_11n_rxba_sync_event(struct mwifiex_private *priv, } } - tlv_buf_left -= (sizeof(*tlv_rxba) + tlv_len); - tmp = (u8 *)tlv_rxba + tlv_len + sizeof(*tlv_rxba); + tlv_buf_left -= (sizeof(tlv_rxba->header) + tlv_len); + tmp = (u8 *)tlv_rxba + sizeof(tlv_rxba->header) + tlv_len; tlv_rxba = (struct mwifiex_ie_types_rxba_sync *)tmp; } }