linux-kernel - [PATCH 3.16 004/136] ipmi: fix unsigned long underflow

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Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Weilong Chen" <chenweilong@...wei.com>,
        "Corey Minyard" <cminyard@...sta.com>
Subject: [PATCH 3.16 004/136] ipmi: fix unsigned long underflow

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Corey Minyard <cminyard@...sta.com>

commit 392a17b10ec4320d3c0e96e2a23ebaad1123b989 upstream.

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@...wei.com>
Signed-off-by: Corey Minyard <cminyard@...sta.com>
Tested-by: Weilong Chen <chenweilong@...wei.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/char/ipmi/ipmi_msghandler.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -4007,7 +4007,8 @@ smi_from_recv_msg(ipmi_smi_t intf, struc
 }
 
 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)
 {
@@ -4020,8 +4021,8 @@ static void check_msg_timeout(ipmi_smi_t
 	if (!ent->inuse)
 		return;
 
-	ent->timeout -= timeout_period;
-	if (ent->timeout > 0) {
+	if (timeout_period < ent->timeout) {
+		ent->timeout -= timeout_period;
 		(*waiting_msgs)++;
 		return;
 	}
@@ -4088,7 +4089,8 @@ static void check_msg_timeout(ipmi_smi_t
 	}
 }
 
-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;