From b72fe9f3cd1b92cbf7dea04ef73a6852a7053fde Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: Thu, 16 Jun 2022 11:38:00 +0200
Subject: [PATCH 01/28] can: mcp251xfd: mcp251xfd_register_get_dev_id(): use
 correct length to read dev_id
Git-commit: 0ff32bfa0e794ccc3601de7158b522bf736fa63c
Patch-mainline: v5.19-rc16
References: git-fixes

The device ID register is 32 bits wide. The driver uses incorrectly
the size of a pointer to a u32 to calculate the length of the SPI
transfer. This results in a read of 2 registers on 64 bit platforms.
This is no problem on the Linux side, as the RX buffer of the SPI
transfer is large enough. In the mpc251xfd chip this results in the
read of an undocumented register. So far no problems were observed.

Fix the length of the SPI transfer to read the device ID register
only.

Link: https://lore.kernel.org/all/20220616094914.244440-1-mkl@pengutronix.de
Fixes: 55e5b97f003e ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Reported-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index cb21ff707702..100cd7d3b244 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -2685,7 +2685,7 @@ mcp251xfd_register_get_dev_id(const struct mcp251xfd_priv *priv,
 	xfer[0].tx_buf = buf_tx;
 	xfer[0].len = sizeof(buf_tx->cmd);
 	xfer[1].rx_buf = buf_rx->data;
-	xfer[1].len = sizeof(dev_id);
+	xfer[1].len = sizeof(*dev_id);
 
 	mcp251xfd_spi_cmd_read_nocrc(&buf_tx->cmd, MCP251XFD_REG_DEVID);
 	err = spi_sync_transfer(priv->spi, xfer, ARRAY_SIZE(xfer));
-- 
2.16.4