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

[David Miller]

From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Date: Wed, 18 Dec 2019 17:21:55 +0800

> 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@xxxxxxxxx>

Applied and queued up for -stable, thanks.