Commit af3c4bf1 authored May 17, 2022 by Duoming Zhou Committed by Greg Kroah-Hartman May 25, 2022

NFC: nci: fix sleep in atomic context bugs caused by nci_skb_alloc



[ Upstream commit 23dd4581350d4ffa23d58976ec46408f8f4c1e16 ]

There are sleep in atomic context bugs when the request to secure
element of st-nci is timeout. The root cause is that nci_skb_alloc
with GFP_KERNEL parameter is called in st_nci_se_wt_timeout which is
a timer handler. The call paths that could trigger bugs are shown below:

    (interrupt context 1)
st_nci_se_wt_timeout
  nci_hci_send_event
    nci_hci_send_data
      nci_skb_alloc(..., GFP_KERNEL) //may sleep

   (interrupt context 2)
st_nci_se_wt_timeout
  nci_hci_send_event
    nci_hci_send_data
      nci_send_data
        nci_queue_tx_data_frags
          nci_skb_alloc(..., GFP_KERNEL) //may sleep

This patch changes allocation mode of nci_skb_alloc from GFP_KERNEL to
GFP_ATOMIC in order to prevent atomic context sleeping. The GFP_ATOMIC
flag makes memory allocation operation could be used in atomic context.

Fixes: ed06aeef ("nfc: st-nci: Rename st21nfcb to st-nci")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220517012530.75714-1-duoming@zju.edu.cn


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent c8a57c3c

net/nfc/nci/data.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -130,7 +130,7 @@ static int nci_queue_tx_data_frags(struct nci_dev *ndev,

		skb_frag = nci_skb_alloc(ndev,
		(NCI_DATA_HDR_SIZE + frag_len),
		GFP_KERNEL);
		GFP_ATOMIC);
		if (skb_frag == NULL) {
		rc = -ENOMEM;
		goto free_exit;

net/nfc/nci/hci.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -165,7 +165,7 @@ static int nci_hci_send_data(struct nci_dev *ndev, u8 pipe,

		i = 0;
		skb = nci_skb_alloc(ndev, conn_info->max_pkt_payload_len +
		NCI_DATA_HDR_SIZE, GFP_KERNEL);
		NCI_DATA_HDR_SIZE, GFP_ATOMIC);
		if (!skb)
		return -ENOMEM;

		@@ -198,7 +198,7 @@ static int nci_hci_send_data(struct nci_dev *ndev, u8 pipe,
		if (i < data_len) {
		skb = nci_skb_alloc(ndev,
		conn_info->max_pkt_payload_len +
		NCI_DATA_HDR_SIZE, GFP_KERNEL);
		NCI_DATA_HDR_SIZE, GFP_ATOMIC);
		if (!skb)
		return -ENOMEM;