Commit b7ac8936 authored Dec 18, 2019 by Jia-Ju Bai Committed by David S. Miller Dec 18, 2019

net: nfc: nci: fix a possible sleep-in-atomic-context bug in nci_uart_tty_receive()



The kernel may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

net/nfc/nci/uart.c, 349:
	nci_skb_alloc in nci_uart_default_recv_buf
net/nfc/nci/uart.c, 255:
	(FUNC_PTR)nci_uart_default_recv_buf in nci_uart_tty_receive
net/nfc/nci/uart.c, 254:
	spin_lock in nci_uart_tty_receive

nci_skb_alloc(GFP_KERNEL) can sleep at runtime.
(FUNC_PTR) means a function pointer is called.

To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC for
nci_skb_alloc().

This bug is found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ddd9b5e3

net/nfc/nci/uart.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -346,7 +346,7 @@ static int nci_uart_default_recv_buf(struct nci_uart nu, const u8 data,
		nu->rx_packet_len = -1;
		nu->rx_skb = nci_skb_alloc(nu->ndev,
		NCI_MAX_PACKET_SIZE,
		GFP_KERNEL);
		GFP_ATOMIC);
		if (!nu->rx_skb)
		return -ENOMEM;
		}

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