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ACPI, extlog: shift wrapping bug in extlog_get_dsm()

PATCH In review Dan Carpenter 1 participant 1 message Nov 5, 2013

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Kernel janitors ACPI
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Dan Carpenter

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PATCH 1/2 ACPI, extlog: shift wrapping bug in extlog_get_dsm()

obj->buffer.pointer is a u8 pointer so we need to cast it to u64 for the 64 bit shift. Otherwise the upper bits are always zero.

I tweaked a couple nearby lines as well to avoid going over the 80 character limit.

Signed-off-by Dan Carpenter <[email protected]>
drivers/acpi/acpi_extlog.c +3 -5
index a6869e1..c4d5e59 100644
@@ -182,11 +182,9 @@ static int extlog_get_dsm(acpi_handle handle, int rev, int func, u64 *ret)
 	obj = (union acpi_object *)buf.pointer;
 	if (obj->type = ACPI_TYPE_INTEGER) {
 		*ret = obj->integer.value;
-	} else if (obj->type = ACPI_TYPE_BUFFER) {
-		if (obj->buffer.length <= 8) {
-			for (i = 0; i < obj->buffer.length; i++)
-				*ret |= (obj->buffer.pointer[i] << (i * 8));
-		}
+	} else if (obj->type = ACPI_TYPE_BUFFER && obj->buffer.length <= 8) {
+		for (i = 0; i < obj->buffer.length; i++)
+			*ret |= ((u64)obj->buffer.pointer[i] << (i * 8));
 	}
 	kfree(buf.pointer);