can: mcp251xfd: mcp251xfd_handle_rxif_one(): fix wrong NULL pointer check

stable inclusion
from stable-5.10.10
commit fd21e00c5e0b0b9333e8cc26ab188f360447eb6d
bugzilla: 47610

--------------------------------

[ Upstream commit ca4c6ebe ]

If alloc_canfd_skb() returns NULL, 'cfg' is an uninitialized variable, so we
should check 'skb' rather than 'cfd' after calling alloc_canfd_skb(priv->ndev,
&cfd).

Fixes: 55e5b97f ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Signed-off-by: NQinglang Miao <miaoqinglang@huawei.com>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20210113073100.79552-1-miaoqinglang@huawei.comSigned-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c

@@ -1432,7 +1432,7 @@ mcp251xfd_handle_rxif_one(struct mcp251xfd_priv *priv,
 	else
 		skb = alloc_can_skb(priv->ndev, (struct can_frame **)&cfd);
 
-	if (!cfd) {
+	if (!skb) {
 		stats->rx_dropped++;
 		return 0;
 	}