Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751962AbdC0FE4 (ORCPT ); Mon, 27 Mar 2017 01:04:56 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:60150 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751911AbdC0FEt (ORCPT ); Mon, 27 Mar 2017 01:04:49 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Mon, 27 Mar 2017 13:04:45 +0800 From: joechang@codeaurora.org To: minyard@acm.org Cc: Joeseph Chang , openipmi-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, anjiandi@qti.qualcomm.com, Corey Minyard Subject: Re: [PATCH] ipmi: Fix kernel panic at ipmi_ssif_thread() In-Reply-To: <6d686ff9-e94b-ddc0-cf9f-13a839acbb08@acm.org> References: <1490252832-20381-1-git-send-email-joechang@qti.qualcomm.com> <6d686ff9-e94b-ddc0-cf9f-13a839acbb08@acm.org> Message-ID: <80838c25e081439b1bfd65acacc91684@codeaurora.org> User-Agent: Roundcube Webmail/1.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5201 Lines: 150 Hi Corey, Thanks your feedback and suggestion. :) I think you are right. It is better to allocate one new local variable to store i2c data and size that will be sent... I create new patch in following according to your suggestion. Could you help to review the patch again? From eec31f51acc7e019fd0dcc512febda86870268d2 Mon Sep 17 00:00:00 2001 From: Joeseph Chang Date: Mon, 27 Mar 2017 10:46:42 +0800 Subject: [PATCH] ipmi: Fix kernel panic at ipmi_ssif_thread() msg_written_handler() may set ssif_info->multi_data to NULL when using ipmitool to write fru. Fix kernel panic at ipmi_ssif_thread() and incorrect ssif_info->multi_pos by adding one local pointer i2c_data to store i2c data and size to send before calling ssif_i2c_send(). With this change, can avoid concurrent access to ssif_info->multi_pos and ssif_info->multi_data at msg_written_handler. Because msg_written_handler can be called at any time after ssif_i2c_send(). --- drivers/char/ipmi/ipmi_ssif.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) mode change 100644 => 100755 drivers/char/ipmi/ipmi_ssif.c diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c old mode 100644 new mode 100755 index cca6e5b..f36f018 --- a/drivers/char/ipmi/ipmi_ssif.c +++ b/drivers/char/ipmi/ipmi_ssif.c @@ -852,6 +852,7 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result, unsigned char *data, unsigned int len) { int rv; + unsigned char *i2c_data; /* We are single-threaded here, so no need for a lock. */ if (result < 0) { @@ -899,6 +900,7 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result, left = 32; /* Length byte. */ ssif_info->multi_data[ssif_info->multi_pos] = left; + i2c_data = ssif_info->multi_data + ssif_info->multi_pos; ssif_info->multi_pos += left; if (left < 32) /* @@ -912,7 +914,7 @@ static void msg_written_handler(struct ssif_info *ssif_info, int result, rv = ssif_i2c_send(ssif_info, msg_written_handler, I2C_SMBUS_WRITE, SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE, - ssif_info->multi_data + ssif_info->multi_pos, + i2c_data, I2C_SMBUS_BLOCK_DATA); if (rv < 0) { /* request failed, just return the error. */ -- 1.9.1 Thank you, Joseph. Corey Minyard 於 2017-03-25 10:53 寫到: > This is incorrect. These values *must* be set before ssif_i2c_send() > is done. > Once ssif_i2c_send() is called, msg_written_handler can be called at > any > time after that, including before where you moved the new code. > > If I understand this correctly, I think you need to add a variable, > maybe named "bytes_to_write" and do > > bytes_to_write = ssif_info->multi_data + ssif_info->multi_pos; > > before the comparison and pass bytes_to_write into > ssif_i2c_send(). > > Thanks, > > -corey > > On 03/23/2017 02:07 AM, Joeseph Chang wrote: >> From: Joeseph Chang >> >> msg_written_handler() may set ssif_info->multi_data to NULL >> when using ipmitool to write fru. >> Change the ssif i2c send data sequence in msg_written_handler() >> to fix NULL pointer kernel panic and incorrect ssif_info->multi_pos. >> >> Signed-off-by: Joeseph Chang >> --- >> drivers/char/ipmi/ipmi_ssif.c | 20 +++++++++++--------- >> 1 file changed, 11 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/char/ipmi/ipmi_ssif.c >> b/drivers/char/ipmi/ipmi_ssif.c >> index cca6e5b..39346ee 100644 >> --- a/drivers/char/ipmi/ipmi_ssif.c >> +++ b/drivers/char/ipmi/ipmi_ssif.c >> @@ -899,21 +899,13 @@ static void msg_written_handler(struct ssif_info >> *ssif_info, int result, >> left = 32; >> /* Length byte. */ >> ssif_info->multi_data[ssif_info->multi_pos] = left; >> - ssif_info->multi_pos += left; >> - if (left < 32) >> - /* >> - * Write is finished. Note that we must end >> - * with a write of less than 32 bytes to >> - * complete the transaction, even if it is >> - * zero bytes. >> - */ >> - ssif_info->multi_data = NULL; >> rv = ssif_i2c_send(ssif_info, msg_written_handler, >> I2C_SMBUS_WRITE, >> SSIF_IPMI_MULTI_PART_REQUEST_MIDDLE, >> ssif_info->multi_data + ssif_info->multi_pos, >> I2C_SMBUS_BLOCK_DATA); >> + >> if (rv < 0) { >> /* request failed, just return the error. */ >> ssif_inc_stat(ssif_info, send_errors); >> @@ -922,6 +914,16 @@ static void msg_written_handler(struct ssif_info >> *ssif_info, int result, >> pr_info("Error from i2c_non_blocking_op(3)\n"); >> msg_done_handler(ssif_info, -EIO, NULL, 0); >> } >> + >> + ssif_info->multi_pos += left; >> + if (left < 32) >> + /* >> + * Write is finished. Note that we must end >> + * with a write of less than 32 bytes to >> + * complete the transaction, even if it is >> + * zero bytes. >> + */ >> + ssif_info->multi_data = NULL; >> } else { >> /* Ready to request the result. */ >> unsigned long oflags, *flags;