linux-kernel - Re: [syzbot] [PATCH net v4] nfc: nci: Fix uninit-value in nci_rx

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Date: Wed, 08 May 2024 17:49:13 -0700
From: syzbot <syzbot+d7b4dc6cd50410152534@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [PATCH net v4] nfc: nci: Fix uninit-value in nci_rx_work

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***

Subject: [PATCH net v4] nfc: nci: Fix uninit-value in nci_rx_work
Author: ryasuoka@...hat.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git main

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index b133dc55304c..0aaff30cb68f 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1463,6 +1463,16 @@ 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, unsigned int header_size)
+{
+	if (skb->len < header_size ||
+	    !nci_plen(skb->data) ||
+	    skb->len < header_size + nci_plen(skb->data)) {
+		return false;
+	}
+	return true;
+}
+
 /* ---- NCI TX Data worker thread ---- */
 
 static void nci_tx_work(struct work_struct *work)
@@ -1516,24 +1526,32 @@ 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) {
 			kfree_skb(skb);
-			kcov_remote_stop();
-			break;
+			continue;
 		}
 
 		/* Process frame */
 		switch (nci_mt(skb->data)) {
 		case NCI_MT_RSP_PKT:
-			nci_rsp_packet(ndev, skb);
+			if (nci_valid_size(skb, NCI_CTRL_HDR_SIZE))
+				nci_rsp_packet(ndev, skb);
+			else
+				kfree_skb(skb);
 			break;
 
 		case NCI_MT_NTF_PKT:
-			nci_ntf_packet(ndev, skb);
+			if (nci_valid_size(skb, NCI_CTRL_HDR_SIZE))
+				nci_ntf_packet(ndev, skb);
+			else
+				kfree_skb(skb);
 			break;
 
 		case NCI_MT_DATA_PKT:
-			nci_rx_data_packet(ndev, skb);
+			if (nci_valid_size(skb, NCI_DATA_HDR_SIZE))
+				nci_rx_data_packet(ndev, skb);
+			else
+				kfree_skb(skb);
 			break;
 
 		default: