nfc: pn533: Fix double free when pn533_fill_fragment_skbs() fails

skb is already freed by dev_kfree_skb in pn533_fill_fragment_skbs,
but follow error handler branch when pn533_fill_fragment_skbs()
fails, skb is freed again, results in double free issue. Fix this
by not free skb in error path of pn533_fill_fragment_skbs.

Fixes: 963a82e07d4e ("NFC: pn533: Split large Tx frames in chunks")
Fixes: 93ad42020c2d ("NFC: pn533: Target mode Tx fragmentation support")
Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/nfc/pn533/pn533.c b/drivers/nfc/pn533/pn533.c
index 787bcbd..a491db4 100644 (file)
--- a/drivers/nfc/pn533/pn533.c
+++ b/drivers/nfc/pn533/pn533.c
@@ -2216,7 +2216,7 @@ static int pn533_fill_fragment_skbs(struct pn533 *dev, struct sk_buff *skb)
                frag = pn533_alloc_skb(dev, frag_size);
                if (!frag) {
                        skb_queue_purge(&dev->fragment_skb);
-                       break;
+                       return -ENOMEM;
                }
 
                if (!dev->tgt_mode) {
@@ -2285,7 +2285,7 @@ static int pn533_transceive(struct nfc_dev *nfc_dev,
                /* jumbo frame ? */
                if (skb->len > PN533_CMD_DATAEXCH_DATA_MAXLEN) {
                        rc = pn533_fill_fragment_skbs(dev, skb);
-                       if (rc <= 0)
+                       if (rc < 0)
                                goto error;
 
                        skb = skb_dequeue(&dev->fragment_skb);
@@ -2353,7 +2353,7 @@ static int pn533_tm_send(struct nfc_dev *nfc_dev, struct sk_buff *skb)
        /* let's split in multiple chunks if size's too big */
        if (skb->len > PN533_CMD_DATAEXCH_DATA_MAXLEN) {
                rc = pn533_fill_fragment_skbs(dev, skb);
-               if (rc <= 0)
+               if (rc < 0)
                        goto error;
 
                /* get the first skb */