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

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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>
This commit is contained in:
Jia-Ju Bai 2019-12-18 17:21:55 +08:00 committed by David S. Miller
parent ddd9b5e3e7
commit b7ac893652
1 changed files with 1 additions and 1 deletions
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2
net/nfc/nci/uart.c
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@ -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;
}