[PATCH] ipmi: fix unsigned long overflow

[PATCH] ipmi: fix unsigned long overflow

[Weilong Chen]

When I set the timeout to a specific value such as 500ms, the timeout
event will not happen in time due to the overflow in function
check_msg_timeout:
...
	ent->timeout -= timeout_period;
	if (ent->timeout > 0)
		return;
...

The type of timeout_period is long, but ent->timeout is unsigned long.
This patch makes the type consistent.

Signed-off-by: Weilong Chen <chenweilong@huawei.com>
---
 drivers/char/ipmi/ipmi_msghandler.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 810b138..4c806e9 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -135,8 +135,8 @@ struct seq_table {
 	unsigned int         inuse : 1;
 	unsigned int         broadcast : 1;
 
-	unsigned long        timeout;
-	unsigned long        orig_timeout;
+	long        timeout;
+	long        orig_timeout;
 	unsigned int         retries_left;
 
 	/*
-- 
1.8.3.1

[PATCH] ipmi: fix unsigned long underflow

[minyard]

From: Corey Minyard <cminyard@mvista.com>

When I set the timeout to a specific value such as 500ms, the timeout
event will not happen in time due to the overflow in function
check_msg_timeout:
...
	ent->timeout -= timeout_period;
	if (ent->timeout > 0)
		return;
...

The type of timeout_period is long, but ent->timeout is unsigned long.
This patch makes the type consistent.

Reported-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
---
I like to keep things consistent (though I obviously messed up here)
and keep variables that should be positive unsigned.

But you are right, there is a bug here and some inconsistency.
This patch changes timeout_period to be unsigned and fixes the
check.  Can you try this out?

 drivers/char/ipmi/ipmi_msghandler.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 810b138..c82d9fd 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -4030,7 +4030,8 @@ smi_from_recv_msg(ipmi_smi_t intf, struct ipmi_recv_msg *recv_msg,
 }
 
 static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
-			      struct list_head *timeouts, long timeout_period,
+			      struct list_head *timeouts,
+			      unsigned long timeout_period,
 			      int slot, unsigned long *flags,
 			      unsigned int *waiting_msgs)
 {
@@ -4043,8 +4044,8 @@ static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
 	if (!ent->inuse)
 		return;
 
-	ent->timeout -= timeout_period;
-	if (ent->timeout > 0) {
+	if (timeout_period < ent->timeout) {
+		ent->timeout -= timeout_period;
 		(*waiting_msgs)++;
 		return;
 	}
@@ -4110,7 +4111,8 @@ static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
 	}
 }
 
-static unsigned int ipmi_timeout_handler(ipmi_smi_t intf, long timeout_period)
+static unsigned int ipmi_timeout_handler(ipmi_smi_t intf,
+					 unsigned long timeout_period)
 {
 	struct list_head     timeouts;
 	struct ipmi_recv_msg *msg, *msg2;
-- 
2.7.4

Re: [PATCH] ipmi: fix unsigned long underflow

[Weilong Chen]

Hi Minyard,

I test this patch, it works.

Thanks.

On 2017/7/30 10:20, minyard@acm.org wrote:
> From: Corey Minyard <cminyard@mvista.com>
>
> When I set the timeout to a specific value such as 500ms, the timeout
> event will not happen in time due to the overflow in function
> check_msg_timeout:
> ...
> 	ent->timeout -= timeout_period;
> 	if (ent->timeout > 0)
> 		return;
> ...
>
> The type of timeout_period is long, but ent->timeout is unsigned long.
> This patch makes the type consistent.
>
> Reported-by: Weilong Chen <chenweilong@huawei.com>
> Signed-off-by: Corey Minyard <cminyard@mvista.com>
> ---
> I like to keep things consistent (though I obviously messed up here)
> and keep variables that should be positive unsigned.
>
> But you are right, there is a bug here and some inconsistency.
> This patch changes timeout_period to be unsigned and fixes the
> check.  Can you try this out?
>
>  drivers/char/ipmi/ipmi_msghandler.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index 810b138..c82d9fd 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -4030,7 +4030,8 @@ smi_from_recv_msg(ipmi_smi_t intf, struct ipmi_recv_msg *recv_msg,
>  }
>
>  static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
> -			      struct list_head *timeouts, long timeout_period,
> +			      struct list_head *timeouts,
> +			      unsigned long timeout_period,
>  			      int slot, unsigned long *flags,
>  			      unsigned int *waiting_msgs)
>  {
> @@ -4043,8 +4044,8 @@ static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
>  	if (!ent->inuse)
>  		return;
>
> -	ent->timeout -= timeout_period;
> -	if (ent->timeout > 0) {
> +	if (timeout_period < ent->timeout) {
> +		ent->timeout -= timeout_period;
>  		(*waiting_msgs)++;
>  		return;
>  	}
> @@ -4110,7 +4111,8 @@ static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
>  	}
>  }
>
> -static unsigned int ipmi_timeout_handler(ipmi_smi_t intf, long timeout_period)
> +static unsigned int ipmi_timeout_handler(ipmi_smi_t intf,
> +					 unsigned long timeout_period)
>  {
>  	struct list_head     timeouts;
>  	struct ipmi_recv_msg *msg, *msg2;
>

Re: [PATCH] ipmi: fix unsigned long underflow

[Corey Minyard]

On 08/07/2017 03:41 AM, Weilong Chen wrote:
> Hi Minyard,
>
> I test this patch, it works.
>
> Thanks.
>

Thanks, I added a Tested-by: for you and it's queued for the next release.
If it's urgent I can send it in now.

I also added this for the stable kernels 3.16 and later.

-corey

> On 2017/7/30 10:20, minyard@acm.org wrote:
>> From: Corey Minyard <cminyard@mvista.com>
>>
>> When I set the timeout to a specific value such as 500ms, the timeout
>> event will not happen in time due to the overflow in function
>> check_msg_timeout:
>> ...
>>     ent->timeout -= timeout_period;
>>     if (ent->timeout > 0)
>>         return;
>> ...
>>
>> The type of timeout_period is long, but ent->timeout is unsigned long.
>> This patch makes the type consistent.
>>
>> Reported-by: Weilong Chen <chenweilong@huawei.com>
>> Signed-off-by: Corey Minyard <cminyard@mvista.com>
>> ---
>> I like to keep things consistent (though I obviously messed up here)
>> and keep variables that should be positive unsigned.
>>
>> But you are right, there is a bug here and some inconsistency.
>> This patch changes timeout_period to be unsigned and fixes the
>> check.  Can you try this out?
>>
>>  drivers/char/ipmi/ipmi_msghandler.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/char/ipmi/ipmi_msghandler.c 
>> b/drivers/char/ipmi/ipmi_msghandler.c
>> index 810b138..c82d9fd 100644
>> --- a/drivers/char/ipmi/ipmi_msghandler.c
>> +++ b/drivers/char/ipmi/ipmi_msghandler.c
>> @@ -4030,7 +4030,8 @@ smi_from_recv_msg(ipmi_smi_t intf, struct 
>> ipmi_recv_msg *recv_msg,
>>  }
>>
>>  static void check_msg_timeout(ipmi_smi_t intf, struct seq_table *ent,
>> -                  struct list_head *timeouts, long timeout_period,
>> +                  struct list_head *timeouts,
>> +                  unsigned long timeout_period,
>>                    int slot, unsigned long *flags,
>>                    unsigned int *waiting_msgs)
>>  {
>> @@ -4043,8 +4044,8 @@ static void check_msg_timeout(ipmi_smi_t intf, 
>> struct seq_table *ent,
>>      if (!ent->inuse)
>>          return;
>>
>> -    ent->timeout -= timeout_period;
>> -    if (ent->timeout > 0) {
>> +    if (timeout_period < ent->timeout) {
>> +        ent->timeout -= timeout_period;
>>          (*waiting_msgs)++;
>>          return;
>>      }
>> @@ -4110,7 +4111,8 @@ static void check_msg_timeout(ipmi_smi_t intf, 
>> struct seq_table *ent,
>>      }
>>  }
>>
>> -static unsigned int ipmi_timeout_handler(ipmi_smi_t intf, long 
>> timeout_period)
>> +static unsigned int ipmi_timeout_handler(ipmi_smi_t intf,
>> +                     unsigned long timeout_period)
>>  {
>>      struct list_head     timeouts;
>>      struct ipmi_recv_msg *msg, *msg2;
>>
>