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 28C34C4167B for ; Mon, 17 Jan 2022 17:11:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241601AbiAQRLZ (ORCPT ); Mon, 17 Jan 2022 12:11:25 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:56410 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241655AbiAQRIL (ORCPT ); Mon, 17 Jan 2022 12:08:11 -0500 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 F0978B8114E; Mon, 17 Jan 2022 17:08:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EAE66C36AEC; Mon, 17 Jan 2022 17:08:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642439287; bh=iyFxWuN2vu/dulDTqndeNcafmcjOaQG2EV3AgqR2eKc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i8Jh+OPzlBudKWD6g0NFJw8U8qsEu2NGmtZJ21DFfTfiFoC6ya329MbX8ymQ+Ofwx TF8XLKohTrYpByOrRthHnfpg6rXHnPFG3FUQm3qDJk9l6SY0cEKtt4wJSX133nmzzg It61Jl1Kkzla05HMheEK37E8LLTL9ZP1Egy+hOBk2EOOipjcL3KZEnxR04IF1k2Bik G9nO7bHy6F9uZ9gAExVR8cVqpw7gx4x0RrbAJqhdRwnNhopNoygmWlakHkT2A6YvG6 5p3tPLeiIv8O/pOxwyp/VTrOftDiQxeJ9ss04Pa6cszrTn3fNmJXhFP8PBCIknwnBY AFThs3Tzjv0hw== 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 4.4 05/12] i2c: i801: Don't silently correct invalid transfer size Date: Mon, 17 Jan 2022 12:07:49 -0500 Message-Id: <20220117170757.1473318-5-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220117170757.1473318-1-sashal@kernel.org> References: <20220117170757.1473318-1-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: stable@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 4399016a6caba..73026c00220c2 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -669,6 +669,11 @@ 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 */ @@ -682,16 +687,6 @@ 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