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Message-ID: <80838c25e081439b1bfd65acacc91684@codeaurora.org>
Date: Mon, 27 Mar 2017 13:04:45 +0800
From: joechang@...eaurora.org
To: minyard@....org
Cc: Joeseph Chang <joechang@....qualcomm.com>,
openipmi-developer@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, anjiandi@....qualcomm.com,
Corey Minyard <tcminyard@...il.com>
Subject: Re: [PATCH] ipmi: Fix kernel panic at ipmi_ssif_thread()
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 <joechang@...eaurora.org>
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 <joechang@...eaurora.org>
>>
>> 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 <joechang@...eaurora.org>
>> ---
>> 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;
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