[PATCH AUTOSEL 4.19 68/84] net: nfc: nci: fix a possible sleep-in-atomic-context bug in nci_uart_tty_receive()
From: Sasha Levin
Date: Fri Dec 27 2019 - 12:46:29 EST
From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
[ 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: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 a66f102c6c01..040576dd73bb 100644
--- a/net/nfc/nci/uart.c
+++ b/net/nfc/nci/uart.c
@@ -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;
}
--
2.20.1