[PATCH 6.19 340/781] net: mctp-i2c: fix duplicate reception of old data

Greg Kroah-Hartman
2026-02-25T01:33:12Z

From: Jian Zhang <zhangjian.3032@bytedance.com>

[ Upstream commit ae4744e173fadd092c43eda4ca92dcb74645225a ]

The MCTP I2C slave callback did not handle I2C_SLAVE_READ_REQUESTED
events. As a result, i2c read event will trigger repeated reception of
old data, reset rx_pos when a read request is received.

Signed-off-by: Jian Zhang <zhangjian.3032@bytedance.com>
Link: https://patch.msgid.link/20260108101829.1140448-1-zhangjian.3032@bytedance.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 2a14e91b6d76 ("mctp i2c: initialise event handler read bytes")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/mctp/mctp-i2c.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/net/mctp/mctp-i2c.c b/drivers/net/mctp/mctp-i2c.c
index f782d93f826ef..ecda1cc36391c 100644
--- a/drivers/net/mctp/mctp-i2c.c
+++ b/drivers/net/mctp/mctp-i2c.c
@@ -242,6 +242,9 @@ static int mctp_i2c_slave_cb(struct i2c_client *client,
return 0;

switch (event) {
+ case I2C_SLAVE_READ_REQUESTED:
+ midev->rx_pos = 0;
+ break;
case I2C_SLAVE_WRITE_RECEIVED:
if (midev->rx_pos < MCTP_I2C_BUFSZ) {
midev->rx_buffer[midev->rx_pos] = *val;
@@ -279,6 +282,9 @@ static int mctp_i2c_recv(struct mctp_i2c_dev *midev)
size_t recvlen;
int status;

+ if (midev->rx_pos == 0)
+ return 0;
+
/* + 1 for the PEC */
if (midev->rx_pos < MCTP_I2C_MINLEN + 1) {
ndev->stats.rx_length_errors++;
--
2.51.0