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Message-Id: <20191218092155.5030-1-baijiaju1990@gmail.com>
Date: Wed, 18 Dec 2019 17:21:55 +0800
From: Jia-Ju Bai <baijiaju1990@...il.com>
To: davem@...emloft.net, gregkh@...uxfoundation.org,
tglx@...utronix.de, allison@...utok.net, alexios.zavras@...el.com,
alexandru.ardelean@...log.com, albin_yang@....com,
dan.carpenter@...cle.com
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] 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@...il.com>
---
net/nfc/nci/uart.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/nfc/nci/uart.c b/net/nfc/nci/uart.c
index 78fe622eba65..11b554ce07ff 100644
--- a/net/nfc/nci/uart.c
+++ b/net/nfc/nci/uart.c
@@ -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;
}
--
2.17.1
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