[PATCH net] nfc: nci: Fix uninit-value in nci_rx_work

[Ryosuke Yasuoka]

syzbot reported the following uninit-value access issue [1]

nci_rx_work() parses received packet from ndev->rx_q. It should be
checked skb->len is non-zero to verify if it is valid before processing
the packet. If skb->len is zero but skb->data is not, such packet is
invalid and should be silently discarded.

Fixes: d24b03535e5e ("nfc: nci: Fix uninit-value in nci_dev_up and nci_ntf_packet")
Reported-and-tested-by: syzbot+d7b4dc6cd50410152534@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=d7b4dc6cd50410152534 [1]
Signed-off-by: Ryosuke Yasuoka <ryasuoka@xxxxxxxxxx>
---
 net/nfc/nci/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index 0d26c8ec9993..b7a020484131 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1516,7 +1516,7 @@ static void nci_rx_work(struct work_struct *work)
 		nfc_send_to_raw_sock(ndev->nfc_dev, skb,
 				     RAW_PAYLOAD_NCI, NFC_DIRECTION_RX);
 
-		if (!nci_plen(skb->data)) {
+		if (!skb->len || !nci_plen(skb->data)) {
 			kfree_skb(skb);
 			break;
 		}
-- 
2.44.0