linux-kernel - [PATCH] acpi: watchdog: properly initialize resources

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Message-Id: <20170915195526.1541309-1-arnd@arndb.de>
Date:   Fri, 15 Sep 2017 21:55:18 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Ryan Kennedy <ryan5544@...il.com>,
        Guenter Roeck <linux@...ck-us.net>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] acpi: watchdog: properly initialize resources

We copy a local resource structure into a list, but only
initialize some of its members, as pointed out by gcc-4.4:

drivers/acpi/acpi_watchdog.c: In function 'acpi_watchdog_init':
drivers/acpi/acpi_watchdog.c:105: error: 'res.child' may be used uninitialized in this function
drivers/acpi/acpi_watchdog.c:105: error: 'res.sibling' may be used uninitialized in this function
drivers/acpi/acpi_watchdog.c:105: error: 'res.parent' may be used uninitialized in this function
drivers/acpi/acpi_watchdog.c:105: error: 'res.desc' may be used uninitialized in this function
drivers/acpi/acpi_watchdog.c:105: error: 'res.name' may be used uninitialized in this function

Newer compilers can presumably optimize the uninitialized access
away entirely and don't warn at all, but rely on the kzalloc()
to zero the structure first. This adds an explicit initialization
to force consistent behavior.

Fixes: 058dfc767008 ("ACPI / watchdog: Add support for WDAT hardware watchdog")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/acpi/acpi_watchdog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/acpi_watchdog.c b/drivers/acpi/acpi_watchdog.c
index bf22c29d2517..11b113f8e367 100644
--- a/drivers/acpi/acpi_watchdog.c
+++ b/drivers/acpi/acpi_watchdog.c
@@ -66,7 +66,7 @@ void __init acpi_watchdog_init(void)
 	for (i = 0; i < wdat->entries; i++) {
 		const struct acpi_generic_address *gas;
 		struct resource_entry *rentry;
-		struct resource res;
+		struct resource res = {};
 		bool found;
 
 		gas = &entries[i].register_region;
-- 
2.9.0