linux-kernel - Re: [PATCH net v2] nfc: nci: Fix uninit-value in nci_dev_up and nci_ntf

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Date: Wed, 20 Mar 2024 14:13:02 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Ryosuke Yasuoka <ryasuoka@...hat.com>
Cc: krzysztof.kozlowski@...aro.org, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	horms@...nel.org, jeremy@...ine.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, syoshida@...hat.com,
	syzbot+7ea9413ea6749baf5574@...kaller.appspotmail.com,
	syzbot+29b5ca705d2e0f4a44d2@...kaller.appspotmail.com
Subject: Re: [PATCH net v2] nfc: nci: Fix uninit-value in nci_dev_up and
 nci_ntf_packet

Wed, Mar 20, 2024 at 01:54:10AM CET, ryasuoka@...hat.com wrote:
>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.

Nit. Instead of talking about "this patch" in this patch description,
you should use imperative mood to tell the codebase what to do.

https://www.kernel.org/doc/html/v6.6/process/submitting-patches.html#describe-your-changes


Patch looks ok.


>
>Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
>Reported-and-tested-by: syzbot+7ea9413ea6749baf5574@...kaller.appspotmail.com
>Reported-and-tested-by: syzbot+29b5ca705d2e0f4a44d2@...kaller.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@...hat.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
>
>