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mctp: serial: Fix starting value for frame check sequence

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[ Upstream commit 2856a62762 ]

RFC1662 defines the start state for the crc16 FCS to be 0xffff, but
we're currently starting at zero.

This change uses the correct start state. We're only early in the
adoption for the serial binding, so there aren't yet any other users to
interface to.

Fixes: a0c2ccd9b5 ("mctp: Add MCTP-over-serial transport binding")
Reported-by: Harsh Tyagi <harshtya@google.com>
Tested-by: Harsh Tyagi <harshtya@google.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jeremy Kerr
2022-12-16 11:44:09 +08:00
committed by Greg Kroah-Hartman
parent b458d349f8
commit a37f6d5541
1 changed files with 4 additions and 2 deletions
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6
drivers/net/mctp/mctp-serial.c
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@@ -35,6 +35,8 @@
#define BYTE_FRAME 0x7e
#define BYTE_ESC 0x7d
#define FCS_INIT 0xffff
static DEFINE_IDA(mctp_serial_ida);
enum mctp_serial_state {
@@ -123,7 +125,7 @@ static void mctp_serial_tx_work(struct work_struct *work)
buf[2] = dev->txlen;
if (!dev->txpos)
dev->txfcs = crc_ccitt(0, buf + 1, 2);
dev->txfcs = crc_ccitt(FCS_INIT, buf + 1, 2);
txlen = write_chunk(dev, buf + dev->txpos, 3 - dev->txpos);
if (txlen <= 0) {
@@ -303,7 +305,7 @@ static void mctp_serial_push_header(struct mctp_serial *dev, unsigned char c)
case 1:
if (c == MCTP_SERIAL_VERSION) {
dev->rxpos++;
dev->rxfcs = crc_ccitt_byte(0, c);
dev->rxfcs = crc_ccitt_byte(FCS_INIT, c);
} else {
dev->rxstate = STATE_ERR;
}