rt2x00: Check for errors from skb_pad() calls

Commit 739fd94 ("rt2x00: Pad beacon to multiple of 32 bits")
added calls to skb_pad() without checking the return value,
which could cause problems if any of those calls does happen
to fail. Add checks to prevent this from happening.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 30 insertions, 6 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2800lib.c b/drivers/net/wireless/rt2x00/rt2800lib.c
index c9bf074342b..7a68a67c506 100644
--- a/drivers/net/wireless/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/rt2x00/rt2800lib.c
@@ -773,13 +773,14 @@ void rt2800_write_beacon(struct queue_entry *entry, struct txentry_desc *txdesc)
         struct skb_frame_desc *skbdesc = get_skb_frame_desc(entry->skb);
         unsigned int beacon_base;
         unsigned int padding_len;
-        u32 reg;
+        u32 orig_reg, reg;
 
         /*
          * Disable beaconing while we are reloading the beacon data,
          * otherwise we might be sending out invalid data.
          */
         rt2800_register_read(rt2x00dev, BCN_TIME_CFG, &reg);
+        orig_reg = reg;
         rt2x00_set_field32(&reg, BCN_TIME_CFG_BEACON_GEN, 0);
         rt2800_register_write(rt2x00dev, BCN_TIME_CFG, reg);
 
@@ -810,7 +811,14 @@ void rt2800_write_beacon(struct queue_entry *entry, struct txentry_desc *txdesc)
          * Write entire beacon with TXWI and padding to register.
          */
         padding_len = roundup(entry->skb->len, 4) - entry->skb->len;
-        skb_pad(entry->skb, padding_len);
+        if (padding_len && skb_pad(entry->skb, padding_len)) {
+                ERROR(rt2x00dev, "Failure padding beacon, aborting\n");
+                /* skb freed by skb_pad() on failure */
+                entry->skb = NULL;
+                rt2800_register_write(rt2x00dev, BCN_TIME_CFG, orig_reg);
+                return;
+        }
+
         beacon_base = HW_BEACON_OFFSET(entry->entry_idx);
         rt2800_register_multiwrite(rt2x00dev, beacon_base, entry->skb->data,
                                    entry->skb->len + padding_len);
diff --git a/drivers/net/wireless/rt2x00/rt61pci.c b/drivers/net/wireless/rt2x00/rt61pci.c
index dd2164d4d57..927a4a3e0ee 100644
--- a/drivers/net/wireless/rt2x00/rt61pci.c
+++ b/drivers/net/wireless/rt2x00/rt61pci.c
@@ -1978,13 +1978,14 @@ static void rt61pci_write_beacon(struct queue_entry *entry,
         struct queue_entry_priv_pci *entry_priv = entry->priv_data;
         unsigned int beacon_base;
         unsigned int padding_len;
-        u32 reg;
+        u32 orig_reg, reg;
 
         /*
          * Disable beaconing while we are reloading the beacon data,
          * otherwise we might be sending out invalid data.
          */
         rt2x00pci_register_read(rt2x00dev, TXRX_CSR9, &reg);
+        orig_reg = reg;
         rt2x00_set_field32(&reg, TXRX_CSR9_BEACON_GEN, 0);
         rt2x00pci_register_write(rt2x00dev, TXRX_CSR9, reg);
 
@@ -2002,7 +2003,14 @@ static void rt61pci_write_beacon(struct queue_entry *entry,
          * Write entire beacon with descriptor and padding to register.
          */
         padding_len = roundup(entry->skb->len, 4) - entry->skb->len;
-        skb_pad(entry->skb, padding_len);
+        if (padding_len && skb_pad(entry->skb, padding_len)) {
+                ERROR(rt2x00dev, "Failure padding beacon, aborting\n");
+                /* skb freed by skb_pad() on failure */
+                entry->skb = NULL;
+                rt2x00pci_register_write(rt2x00dev, TXRX_CSR9, orig_reg);
+                return;
+        }
+
         beacon_base = HW_BEACON_OFFSET(entry->entry_idx);
         rt2x00pci_register_multiwrite(rt2x00dev, beacon_base,
                                       entry_priv->desc, TXINFO_SIZE);
diff --git a/drivers/net/wireless/rt2x00/rt73usb.c b/drivers/net/wireless/rt2x00/rt73usb.c
index 5ff72deea8d..6e9981a1dd7 100644
--- a/drivers/net/wireless/rt2x00/rt73usb.c
+++ b/drivers/net/wireless/rt2x00/rt73usb.c
@@ -1533,13 +1533,14 @@ static void rt73usb_write_beacon(struct queue_entry *entry,
         struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
         unsigned int beacon_base;
         unsigned int padding_len;
-        u32 reg;
+        u32 orig_reg, reg;
 
         /*
          * Disable beaconing while we are reloading the beacon data,
          * otherwise we might be sending out invalid data.
          */
         rt2x00usb_register_read(rt2x00dev, TXRX_CSR9, &reg);
+        orig_reg = reg;
         rt2x00_set_field32(&reg, TXRX_CSR9_BEACON_GEN, 0);
         rt2x00usb_register_write(rt2x00dev, TXRX_CSR9, reg);
 
@@ -1563,7 +1564,14 @@ static void rt73usb_write_beacon(struct queue_entry *entry,
          * Write entire beacon with descriptor and padding to register.
          */
         padding_len = roundup(entry->skb->len, 4) - entry->skb->len;
-        skb_pad(entry->skb, padding_len);
+        if (padding_len && skb_pad(entry->skb, padding_len)) {
+                ERROR(rt2x00dev, "Failure padding beacon, aborting\n");
+                /* skb freed by skb_pad() on failure */
+                entry->skb = NULL;
+                rt2x00usb_register_write(rt2x00dev, TXRX_CSR9, orig_reg);
+                return;
+        }
+
         beacon_base = HW_BEACON_OFFSET(entry->entry_idx);
         rt2x00usb_register_multiwrite(rt2x00dev, beacon_base, entry->skb->data,
                                       entry->skb->len + padding_len);