linux-kernel - [PATCH] acpi/osl: clear high bits in acpi_os_read

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Date:	Mon, 7 Jul 2014 15:38:53 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>
CC:	<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [PATCH] acpi/osl: clear high bits in acpi_os_read_memory value

If one looks at acpi_os_read_port() it is very similar to the
acpi_os_read_memory() aside from the underlying I/O method.
However we zero out the u32 in the former and not in the latter,
when it seems prudent to do so in both.

This was found by quasi-random code inspection, and as such there
is no known symptom or bug to associate with possibly having stale
data in the high bits of "value".

Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/acpi/osl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index bad25b070fe0..a7373f1f31c8 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -953,6 +953,7 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u64 *value, u32 width)
 	if (!value)
 		value = &dummy;
 
+	*value = 0;
 	switch (width) {
 	case 8:
 		*(u8 *) value = readb(virt_addr);
-- 
1.9.2

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