Patch "hostap: avoid uninitialized variable use in hfa384x_get_rid" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

hostap: avoid uninitialized variable use in hfa384x_get_rid

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
hostap-avoid-uninitialized-variable-use-in-hfa384x_get_rid.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Arnd Bergmann <[email protected]>
Date: Thu, 28 Jan 2016 22:58:28 +0100
Subject: hostap: avoid uninitialized variable use in hfa384x_get_rid

From: Arnd Bergmann <[email protected]>

commit 48dc5fb3ba53b20418de8514700f63d88c5de3a3 upstream.

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) {

This restructures the function as suggested by Russell King, to make it more readable and get more reliable error handling, by handling each failure mode using a goto.

---
 drivers/net/wireless/hostap/hostap_hw.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

@@ -836,25 +836,30 @@ static int hfa384x_get_rid(struct net_de
 	spin_lock_bh(&local->baplock);
 
 	res = hfa384x_setup_bap(dev, BAP0, rid, 0);
-	if (!res)
-		res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
+	if (res)
+		goto unlock;
+
+	res = hfa384x_from_bap(dev, BAP0, &rec, sizeof(rec));
+	if (res)
+		goto unlock;
 
 	if (le16_to_cpu(rec.len) == 0) {
 		/* RID not available */
 		res = -ENODATA;
+		goto unlock;
 	}
 
 	rlen = (le16_to_cpu(rec.len) - 1) * 2;
-	if (!res && exact_len && rlen != len) {
+	if (exact_len && rlen != len) {
 		printk(KERN_DEBUG "%s: hfa384x_get_rid - RID len mismatch: "
 		       "rid=0x%04x, len=%d (expected %d)\n",
 		       dev->name, rid, rlen, len);
 		res = -ENODATA;
 	}
 
-	if (!res)
-		res = hfa384x_from_bap(dev, BAP0, buf, len);
+	res = hfa384x_from_bap(dev, BAP0, buf, len);
 
+unlock:
 	spin_unlock_bh(&local->baplock);
 	mutex_unlock(&local->rid_bap_mtx);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/tty-nozomi-avoid-a-harmless-gcc-warning.patch queue-4.4/gfs2-avoid-uninitialized-variable-warning.patch queue-4.4/hostap-avoid-uninitialized-variable-use-in-hfa384x_get_rid.patch