[patch 10/47] w1: w1 temp calculation overflow fix

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

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

From: Ian Dall <ian@xxxxxxxxxxxxxxxxxxxxx>

commit 507e2fbaaacb6f164b4125b87c5002f95143174b upstream.

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=12646

When the temperature exceeds 32767 milli-degrees the temperature overflows
to -32768 millidegrees.  These are bothe well within the -55 - +125 degree
range for the sensor.

Fix overflow in left-shift of a u8.

Signed-off-by: Ian Dall <ian@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Evgeniy Polyakov <zbr@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/w1/slaves/w1_therm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -113,7 +113,7 @@ static struct w1_therm_family_converter 
 
 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 {
-	s16 t = (rom[1] << 8) | rom[0];
+	int t = ((s16)rom[1] << 8) | rom[0];
 	t = t*1000/16;
 	return t;
 }

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