NFC: digital: Rework ACK PDU handling in initiator mode

With this patch, ACK PDU sk_buffs are now freed and code has been
refactored for better errors handling.

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 27 insertions, 13 deletions

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index e0268777ab18..03bfc74745f7 100644
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -782,6 +782,12 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                 break;
 
         case DIGITAL_NFC_DEP_PFB_ACK_NACK_PDU:
+                if (DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) {
+                        PROTOCOL_ERR("14.12.4.5");
+                        rc = -EIO;
+                        goto exit;
+                }
+
                 if (DIGITAL_NFC_DEP_PFB_PNI(pfb) != ddev->curr_nfc_dep_pni) {
                         PROTOCOL_ERR("14.12.3.3");
                         rc = -EIO;
@@ -791,22 +797,25 @@ static void digital_in_recv_dep_res(struct nfc_digital_dev *ddev, void *arg,
                 ddev->curr_nfc_dep_pni =
                         DIGITAL_NFC_DEP_PFB_PNI(ddev->curr_nfc_dep_pni + 1);
 
-                if (ddev->chaining_skb && !DIGITAL_NFC_DEP_NACK_BIT_SET(pfb)) {
-                        kfree_skb(ddev->saved_skb);
-                        ddev->saved_skb = NULL;
+                if (!ddev->chaining_skb) {
+                        PROTOCOL_ERR("14.12.4.3");
+                        rc = -EIO;
+                        goto exit;
+                }
 
-                        rc = digital_in_send_dep_req(ddev, NULL,
-                                                     ddev->chaining_skb,
-                                                     ddev->data_exch);
-                        if (rc)
-                                goto error;
+                /* The initiator has received a valid ACK. Free the last sent
+                 * PDU and keep on sending chained skb.
+                 */
+                kfree_skb(ddev->saved_skb);
+                ddev->saved_skb = NULL;
 
-                        return;
-                }
+                rc = digital_in_send_dep_req(ddev, NULL,
+                                             ddev->chaining_skb,
+                                             ddev->data_exch);
+                if (rc)
+                        goto error;
 
-                pr_err("Received a ACK/NACK PDU\n");
-                rc = -EINVAL;
-                goto exit;
+                goto free_resp;
 
         case DIGITAL_NFC_DEP_PFB_SUPERVISOR_PDU:
                 if (!DIGITAL_NFC_DEP_PFB_IS_TIMEOUT(pfb)) { /* ATN */
@@ -839,6 +848,11 @@ error:
 
         if (rc)
                 kfree_skb(resp);
+
+        return;
+
+free_resp:
+        dev_kfree_skb(resp);
 }
 
 int digital_in_send_dep_req(struct nfc_digital_dev *ddev,