Re: [Openipmi-developer] [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, miny...@acm.org wrote:

From: Corey Minyard <cminy...@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 <chenweil...@huawei.com>
Signed-off-by: Corey Minyard <cminy...@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;

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