netdev - [PATCH net-next 15/36] can: mcp251xfd: mcp251xfd_regmap_crc_read(): ignore CRC error only if solely OSC register is read

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220224082726.3000007-16-mkl@pengutronix.de>
Date:   Thu, 24 Feb 2022 09:27:05 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net-next 15/36] can: mcp251xfd: mcp251xfd_regmap_crc_read(): ignore CRC error only if solely OSC register is read

MCP251XFD_REG_OSC is the first register the driver reads from. The
chip may be in deep sleep and the SPI transfer (i.e. the assertion of
the CS) will wake the chip up. This takes about 3ms. The CRC of this
transfer is wrong, or there isn't any chip at all, in this case the
CRC will be wrong, too. The driver ignores the CRC error and returns
the read data to the caller.

To avoid any confusion, this patch changes the
mcp251xfd_regmap_crc_read() function to only ignore the CRC error if
solely the OSC register is read. So when reading more than the OSC
registers at once, CRC errors are not ignored.

Link: https://lore.kernel.org/all/20220207131047.282110-3-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
index 7b120c716228..8112f8df22a6 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
@@ -368,7 +368,7 @@ mcp251xfd_regmap_crc_read(void *context,
 		 * to the caller. It will take care of both cases.
 		 *
 		 */
-		if (reg == MCP251XFD_REG_OSC) {
+		if (reg == MCP251XFD_REG_OSC && val_len == sizeof(__le32)) {
 			err = 0;
 			goto out;
 		}
-- 
2.34.1