From mboxrd@z Thu Jan 1 00:00:00 1970 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 43654C433F5 for ; Mon, 17 Jan 2022 17:16:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239465AbiAQRQN (ORCPT ); Mon, 17 Jan 2022 12:16:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243659AbiAQRMh (ORCPT ); Mon, 17 Jan 2022 12:12:37 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3911CC08E814; Mon, 17 Jan 2022 09:07:35 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id EC4FBB81145; Mon, 17 Jan 2022 17:07:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC604C36AED; Mon, 17 Jan 2022 17:07:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642439252; bh=Nnp6w8GL4hiQozY8T/6HlO69LhX6+pjDvbt3rnlGots=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AW9/ZBTDnt2dLIHYx1hrdXknbhnuDKaHmZsbrEmAKmJnl8MNe5FvYkw2ekmw1f1LV jUceZ0kaxbutjfwCA1RGcMw4LKzRftk72gPA4UNUkPaOxDFfLeUnpfxRZxDrI+4pSr eCiLdMZu4p2u9K5Gyh11TYMvrV0mlYqIyTo25d/GbBcTYCqHpiAcDpVa5ulYOcHO95 mYu/FA5AT4jpP8UW3Yl8kYJ9ziC8jZG8deRBi1jQK4wlqEpXWGdNp1OH8bc6o1rwUu 4Ba+ZhAvM5MvuXq+kMzZdtl0q7x+OS3GL7ejDBaa0zxgMbTtJqcpiDw9ofBf4dEQOv UkoSFocNBzkIw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Heiner Kallweit , Jean Delvare , Wolfram Sang , Sasha Levin , jdelvare@suse.com, linux-i2c@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 05/13] i2c: i801: Don't silently correct invalid transfer size Date: Mon, 17 Jan 2022 12:07:13 -0500 Message-Id: <20220117170722.1473137-5-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220117170722.1473137-1-sashal@kernel.org> References: <20220117170722.1473137-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Heiner Kallweit [ Upstream commit effa453168a7eeb8a562ff4edc1dbf9067360a61 ] If an invalid block size is provided, reject it instead of silently changing it to a supported value. Especially critical I see the case of a write transfer with block length 0. In this case we have no guarantee that the byte we would write is valid. When silently reducing a read to 32 bytes then we don't return an error and the caller may falsely assume that we returned the full requested data. If this change should break any (broken) caller, then I think we should fix the caller. Signed-off-by: Heiner Kallweit Reviewed-by: Jean Delvare Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-i801.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c index 0e04b27e3158d..b577c64f3b3ec 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -762,6 +762,11 @@ static int i801_block_transaction(struct i801_priv *priv, int result = 0; unsigned char hostc; + if (read_write == I2C_SMBUS_READ && command == I2C_SMBUS_BLOCK_DATA) + data->block[0] = I2C_SMBUS_BLOCK_MAX; + else if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX) + return -EPROTO; + if (command == I2C_SMBUS_I2C_BLOCK_DATA) { if (read_write == I2C_SMBUS_WRITE) { /* set I2C_EN bit in configuration register */ @@ -775,16 +780,6 @@ static int i801_block_transaction(struct i801_priv *priv, } } - if (read_write == I2C_SMBUS_WRITE - || command == I2C_SMBUS_I2C_BLOCK_DATA) { - if (data->block[0] < 1) - data->block[0] = 1; - if (data->block[0] > I2C_SMBUS_BLOCK_MAX) - data->block[0] = I2C_SMBUS_BLOCK_MAX; - } else { - data->block[0] = 32; /* max for SMBus block reads */ - } - /* Experience has shown that the block buffer can only be used for SMBus (not I2C) block transactions, even though the datasheet doesn't mention this limitation. */ -- 2.34.1