watchdog: w83977f_wdt: underflow in wdt_set_timeout()

Dan Carpenter · Wim Van Sebroeck · commit 62ed853c7de7 · 2015-11-23T08:59:30.000+01:00
"t" is controlled by the user.  If "t" is a very large integer then it
could lead to a negative "tmrval".  We cap the upper bound of "tmrval"
but, in the current code, we allow negatives.  This is a bug and it
causes a static checker warning.  Let's make "tmrval" unsigned to avoid
this problem.

Signed-off-by: Dan Carpenter &lt;dan.carpenter@oracle.com&gt;
Reviewed-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Wim Van Sebroeck &lt;wim@iguana.be&gt;
diff --git a/drivers/watchdog/w83977f_wdt.c b/drivers/watchdog/w83977f_wdt.c
@@ -224,7 +224,7 @@ static int wdt_keepalive(void)
 
 static int wdt_set_timeout(int t)
 {
-	int tmrval;
+	unsigned int tmrval;
 
 	/*
 	 * Convert seconds to watchdog counter time units, rounding up.

Original file line number	Diff line number	Diff line change
`@@ -224,7 +224,7 @@ static int wdt_keepalive(void)`
`224`	`224`
`225`	`225`	`static int wdt_set_timeout(int t)`
`226`	`226`	`{`
`227`		`- int tmrval;`
	`227`	`+ unsigned int tmrval;`
`228`	`228`
`229`	`229`	`/*`
`230`	`230`	`* Convert seconds to watchdog counter time units, rounding up.`