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Commit 8674b26c authored by Jia-Ju Bai's avatar Jia-Ju Bai Committed by Greg Kroah-Hartman
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net: nfc: nci: fix a possible sleep-in-atomic-context bug in nci_uart_tty_receive() 



[ Upstream commit b7ac893652cafadcf669f78452329727e4e255cc ]

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: default avatarJia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0d8373f4

net/nfc/nci/uart.c

+1 −1
Original line number Diff line number Diff line
@@ -348,7 +348,7 @@ 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;

		}