[PATCH v2 3/3] mfd: rave-sp: Check received frame length before accepting next byte

[Andrey Smirnov <andrew.smirnov@gmail.com>]

Check received frame length _before_ accepting next byte in order to
avoid incorrectly rejecting payloads that are RAVE_SP_RX_BUFFER_SIZE
long.

Cc: linux-kernel@vger.kernel.org
Cc: cphealy@gmail.com
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Tested-by: Lucas Stach <l.stach@pengutronix.de>
Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 drivers/mfd/rave-sp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/rave-sp.c b/drivers/mfd/rave-sp.c
index 5c1442fa2308..7db1b32d61e2 100644
--- a/drivers/mfd/rave-sp.c
+++ b/drivers/mfd/rave-sp.c
@@ -546,8 +546,6 @@ static int rave_sp_receive_buf(struct serdev_device *serdev,
 			/* FALLTHROUGH */
 
 		case RAVE_SP_EXPECT_ESCAPED_DATA:
-			deframer->data[deframer->length++] = byte;
-
 			if (deframer->length == sizeof(deframer->data)) {
 				dev_warn(dev, "Bad frame: Too long\n");
 				/*
@@ -562,6 +560,8 @@ static int rave_sp_receive_buf(struct serdev_device *serdev,
 				goto reset_framer;
 			}
 
+			deframer->data[deframer->length++] = byte;
+
 			/*
 			 * We've extracted out special byte, now we
 			 * can go back to regular data collecting
-- 
2.14.3