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 BCED9C433F5 for ; Mon, 17 Jan 2022 17:03:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242259AbiAQRD1 (ORCPT ); Mon, 17 Jan 2022 12:03:27 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:51548 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241976AbiAQRBr (ORCPT ); Mon, 17 Jan 2022 12:01:47 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 1B6D66120D; Mon, 17 Jan 2022 17:01:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1E39C36AEC; Mon, 17 Jan 2022 17:01:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642438905; bh=3cmUl0Kng61V5pxa0ERWvC6ByxCde87qlfadGwheNM8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AiTvVW+PXcODuBwlvDvZ50dIwlBZ3tGwnPy+RMWJCDNLBqxAUko10+Zc23cwDvoo4 UGTzJoXWPDL5HMT+IGwfhTfDIh39h4oK4R3HuM9mZvA7mvFh0VA+PyJjff3cp2Q1qt +yEv6AW9ununE3EsYL7P0z/UzVDwF2/fVc7jJ4kok0h//PzPaGSnp2cVIuhMjfaWLF DQJDf8qBj/V12CbMSR0FQL1z1uJc08U1YzXJbnhNlT7fb+37u16mtvLkc5EuFm1+d6 UHWAwOXlJQu+yEfEUwDRiZWU9KfmYbEE6SFc0Dsj8QwWYYVE2chFeDvSYU2bPanK1r LQIWCvGnf3PYw== 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 5.15 08/44] i2c: i801: Don't silently correct invalid transfer size Date: Mon, 17 Jan 2022 12:00:51 -0500 Message-Id: <20220117170127.1471115-8-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220117170127.1471115-1-sashal@kernel.org> References: <20220117170127.1471115-1-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 1f929e6c30bea..98e39a17fb830 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -763,6 +763,11 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data * 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 */ @@ -776,16 +781,6 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data * } } - 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