Hello Christophe Ricard,
The patch c490c557b67f: "NFC: st21nfca: Fix some skb memory leaks"
from Jan 25, 2015, leads to the following static checker warning:
drivers/nfc/st21nfca/core.c:742 st21nfca_hci_complete_target_discovered()
warn: 'nfcid_skb' was already freed.
drivers/nfc/st21nfca/core.c
712 /* NFC Forum Digital Protocol Table 44 */
713 if (target->sensf_res[0] == 0x01 &&
714 target->sensf_res[1] == 0xfe)
715 target->supported_protocols =
716 NFC_PROTO_NFC_DEP_MASK;
717 else
718 target->supported_protocols =
719 NFC_PROTO_FELICA_MASK;
720 } else {
721 kfree_skb(nfcid_skb);
^^^^^^^^^^^^^^^^^^^^
Freed.
722 /* P2P in type A */
723 r = nfc_hci_get_param(hdev, ST21NFCA_RF_READER_F_GATE,
724 ST21NFCA_RF_READER_F_NFCID1,
725 &nfcid_skb);
^^^^^^^^^^
This is set to a different new skb on some error paths but if we return
-EADDRNOTAVAIL then it's still the same freed skb.
726 if (r < 0)
727 goto exit;
^^^^^^^^^
We hit this goto and double free.
728
729 if (nfcid_skb->len > NFC_NFCID1_MAXSIZE) {
730 r = -EPROTO;
731 goto exit;
732 }
733 memcpy(target->sensf_res, nfcid_skb->data,
734 nfcid_skb->len);
735 target->sensf_res_len = nfcid_skb->len;
736 target->supported_protocols = NFC_PROTO_NFC_DEP_MASK;
737 }
738 target->hci_reader_gate = ST21NFCA_RF_READER_F_GATE;
739 }
740 r = 1;
741 exit:
742 kfree_skb(nfcid_skb);
743 return r;
744 }
regards,
dan carpenter
