[PATCH 5.4 137/202] nfc: nci: Fix uninit-value in nci_rx_work

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5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ryosuke Yasuoka <ryasuoka@xxxxxxxxxx>

[ Upstream commit e4a87abf588536d1cdfb128595e6e680af5cf3ed ]

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

nci_rx_work() parses received packet from ndev->rx_q. It should be
validated header size, payload size and total packet size before
processing the packet. If an invalid packet is detected, it 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>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/nfc/nci/core.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index 701c3752bda09..61b12281ec47c 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1449,6 +1449,19 @@ int nci_core_ntf_packet(struct nci_dev *ndev, __u16 opcode,
 				 ndev->ops->n_core_ops);
 }
 
+static bool nci_valid_size(struct sk_buff *skb)
+{
+	BUILD_BUG_ON(NCI_CTRL_HDR_SIZE != NCI_DATA_HDR_SIZE);
+	unsigned int hdr_size = NCI_CTRL_HDR_SIZE;
+
+	if (skb->len < hdr_size ||
+	    !nci_plen(skb->data) ||
+	    skb->len < hdr_size + nci_plen(skb->data)) {
+		return false;
+	}
+	return true;
+}
+
 /* ---- NCI TX Data worker thread ---- */
 
 static void nci_tx_work(struct work_struct *work)
@@ -1499,7 +1512,7 @@ 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 (!nci_valid_size(skb)) {
 			kfree_skb(skb);
 			break;
 		}
-- 
2.43.0







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