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From: Ryosuke Yasuoka <ryasuoka@redhat.com>
To: krzysztof.kozlowski@linaro.org,
	davem@davemloft.net,
	edumazet@google.com,
	kuba@kernel.org,
	pabeni@redhat.com,
	horms@kernel.org,
	jeremy@jcline.org
Cc: Ryosuke Yasuoka <ryasuoka@redhat.com>,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	syoshida@redhat.com,
	syzbot+7ea9413ea6749baf5574@syzkaller.appspotmail.com,
	syzbot+29b5ca705d2e0f4a44d2@syzkaller.appspotmail.com
Subject: [PATCH net v2] nfc: nci: Fix uninit-value in nci_dev_up and nci_ntf_packet
Date: Wed, 20 Mar 2024 09:54:10 +0900
Message-ID: <20240320005412.905060-1-ryasuoka@redhat.com>
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syzbot reported the following uninit-value access issue [1][2]:

nci_rx_work() parses and processes received packet. When the payload
length is zero, each message type handler reads uninitialized payload
and KMSAN detects this issue. The receipt of a packet with a zero-size
payload is considered unexpected, and therefore, such packets should be
silently discarded.

This patch resolved this issue by checking payload size before calling
each message type handler codes.

Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
Reported-and-tested-by: syzbot+7ea9413ea6749baf5574@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+29b5ca705d2e0f4a44d2@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7ea9413ea6749baf5574 [1]
Closes: https://syzkaller.appspot.com/bug?extid=29b5ca705d2e0f4a44d2 [2]
Signed-off-by: Ryosuke Yasuoka <ryasuoka@redhat.com>
---

v2
- Fix typo in commit message
- Remove Call Trace from commit message that syzbot reported. Make it
  shorter than the previous version.
- Check the payload length in earlier code path. And it can address
  another reported syzbot bug too. [2]

v1
https://lore.kernel.org/all/20240312145658.417288-1-ryasuoka@redhat.com/


 net/nfc/nci/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index 6c9592d05120..f471fc54c6a1 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1512,6 +1512,11 @@ 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)) {
+			kfree_skb(skb);
+			break;
+		}
+
 		/* Process frame */
 		switch (nci_mt(skb->data)) {
 		case NCI_MT_RSP_PKT:
-- 
2.44.0