nfc: nci: fix possible NULL pointer dereference in send_acknowledge()

Handle memory allocation failure from nci_skb_alloc() (calling
alloc_skb()) to avoid possible NULL pointer dereference.

Reported-by: 黄思聪 <[email protected]>
Fixes: 391d8a2 ("NFC: Add NCI over SPI receive")
Cc: <[email protected]>
Signed-off-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: krzk

net/nfc/nci/spi.c

@@ -151,6 +151,8 @@ static int send_acknowledge(struct nci_spi *nspi, u8 acknowledge)
 	int ret;
 
 	skb = nci_skb_alloc(nspi->ndev, 0, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
 
 	/* add the NCI SPI header to the start of the buffer */
 	hdr = skb_push(skb, NCI_SPI_HDR_LEN);