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 80022C433F5 for ; Mon, 17 Jan 2022 17:13:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243239AbiAQRNH (ORCPT ); Mon, 17 Jan 2022 12:13:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241464AbiAQRLP (ORCPT ); Mon, 17 Jan 2022 12:11:15 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 860A5C061781; Mon, 17 Jan 2022 09:06:54 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 67C626128E; Mon, 17 Jan 2022 17:06:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12C4EC36AED; Mon, 17 Jan 2022 17:06:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642439213; bh=yNneMOoQvQQmJG7O7bWEOtcq/cm7Q7vMIAyMICcbcwk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rRFkKejf8vzrQns+XFd+4OXCtAgFQeCt5AA3yyFENsbhBeDNLWw5rZ+jGwGqZqo6b 6Mprh5kVTLMt+dee7y8kP/7/VEnXkEEZEehivoCvcn3XbcA4ipn881Zij8aE1pIlyU 89AIwxUvppjRTGtfbhR9MGFye1UO4s7SNbO/8nXxvxOMyWJ3UWU1c9/Z6gwMM/eAx2 qaLpuTiR4Auw1UTtUvOlxCzo5HvEfPfNT93JfBh29vq0d3Xz2h5ajR3VYz1H2/F4Up Xoc4OhX9hw5xoxr7wXgnDhkwNSjcl6dAfKzCQ+6F8TuJqVfSwT2Puuw9n1SAYXS0LN SzrUN8L4+F8eA== 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 4.14 07/16] i2c: i801: Don't silently correct invalid transfer size Date: Mon, 17 Jan 2022 12:06:29 -0500 Message-Id: <20220117170638.1472900-7-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220117170638.1472900-1-sashal@kernel.org> References: <20220117170638.1472900-1-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-i2c@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 7b1654b0fb6db..c817e3d4b52b8 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -769,6 +769,11 @@ 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 */ @@ -782,16 +787,6 @@ 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