[PATCH 3.18 33/47] hostap: avoid uninitialized variable use in hfa384x_get_rid

Greg Kroah-Hartman
2017-04-28T08:35:15Z

From: Arnd Bergmann <arnd@arndb.de>

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.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/net/wireless/hostap/hostap_hw.c
+++ b/drivers/net/wireless/hostap/hostap_hw.c
@@ -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);