From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751421AbdIEHKB (ORCPT ); Tue, 5 Sep 2017 03:10:01 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:37092 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750704AbdIEHJw (ORCPT ); Tue, 5 Sep 2017 03:09:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stephen Douthit , Dan Priamo , Neil Horman , Wolfram Sang Subject: [PATCH 3.18 1/9] i2c: ismt: Dont duplicate the receive length for block reads Date: Tue, 5 Sep 2017 09:09:35 +0200 Message-Id: <20170905070901.956905322@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170905070901.809390741@linuxfoundation.org> References: <20170905070901.809390741@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephen Douthit commit b6c159a9cb69c2cf0bf59d4e12c3a2da77e4d994 upstream. According to Table 15-14 of the C2000 EDS (Intel doc #510524) the rx data pointed to by the descriptor dptr contains the byte count. desc->rxbytes reports all bytes read on the wire, including the "byte count" byte. So if a device sends 4 bytes in response to a block read, on the wire and in the DMA buffer we see: count data1 data2 data3 data4 0x04 0xde 0xad 0xbe 0xef That's what we want to return in data->block to the next level. Instead we were actually prefixing that with desc->rxbytes: bad count count data1 data2 data3 data4 0x05 0x04 0xde 0xad 0xbe 0xef This was discovered while developing a BMC solution relying on the ipmi_ssif.c driver which was trying to interpret the bogus length field as part of the IPMI response. Signed-off-by: Stephen Douthit Tested-by: Dan Priamo Acked-by: Neil Horman Signed-off-by: Wolfram Sang Signed-off-by: Greg Kroah-Hartman --- drivers/i2c/busses/i2c-ismt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/i2c/busses/i2c-ismt.c +++ b/drivers/i2c/busses/i2c-ismt.c @@ -340,8 +340,8 @@ static int ismt_process_desc(const struc break; case I2C_SMBUS_BLOCK_DATA: case I2C_SMBUS_I2C_BLOCK_DATA: - memcpy(&data->block[1], dma_buffer, desc->rxbytes); - data->block[0] = desc->rxbytes; + memcpy(data->block, dma_buffer, desc->rxbytes); + data->block[0] = desc->rxbytes - 1; break; } return 0;