linux-kernel - [PATCH] hostap: avoid uninitialized variable use in hfa384x_get

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Date:	Wed, 27 Jan 2016 14:45:26 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Jouni Malinen <j@...fi>, Kalle Valo <kvalo@...eaurora.org>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Arnd Bergmann <arnd@...db.de>, linux-wireless@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] hostap: avoid uninitialized variable use in hfa384x_get_rid

The driver reads a value from hfa384x_from_bap(), which may fail,
and then assigns the value to a local variable. gcc detects that
in in the failure case, the 'rlen' variable now contains
uninitialized data:

In file included from ../drivers/net/wireless/intersil/hostap/hostap_pci.c:220:0:
drivers/net/wireless/intersil/hostap/hostap_hw.c: In function 'hfa384x_get_rid':
drivers/net/wireless/intersil/hostap/hostap_hw.c:842:5: warning: 'rec' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if (le16_to_cpu(rec.len) == 0) {

To ensure we get consistent error handling here, this changes the code
to only set rlen if we actually read data correctly, which also takes
care of the warning.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/net/wireless/intersil/hostap/hostap_hw.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/intersil/hostap/hostap_hw.c b/drivers/net/wireless/intersil/hostap/hostap_hw.c
index 6df3ee561d52..6dbf8ee9490a 100644
--- a/drivers/net/wireless/intersil/hostap/hostap_hw.c
+++ b/drivers/net/wireless/intersil/hostap/hostap_hw.c
@@ -839,12 +839,15 @@ static int hfa384x_get_rid(struct net_device *dev, u16 rid, void *buf, int len,
 	if (!res)
 		res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
 
-	if (le16_to_cpu(rec.len) == 0) {
-		/* RID not available */
-		res = -ENODATA;
+	if (!res) {
+		if (le16_to_cpu(rec.len) == 0) {
+			/* RID not available */
+			res = -ENODATA;
+		}
+
+		rlen = (le16_to_cpu(rec.len) - 1) * 2;
 	}
 
-	rlen = (le16_to_cpu(rec.len) - 1) * 2;
 	if (!res && exact_len && rlen != len) {
 		printk(KERN_DEBUG "%s: hfa384x_get_rid - RID len mismatch: "
 		       "rid=0x%04x, len=%d (expected %d)\n",
-- 
2.7.0