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SubjectRe: [PATCH] net: nfc: nci: fix a possible sleep-in-atomic-context bug in nci_uart_tty_receive()
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From: Jia-Ju Bai <baijiaju1990@gmail.com>
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@gmail.com>

Applied and queued up for -stable, thanks.

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