linux-kernel - [PATCH] i2c: mv64xxx: prevent illegal pointer access

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Message-ID: <20250729084523.3220002-1-enachman@marvell.com>
Date: Tue, 29 Jul 2025 11:45:23 +0300
From: <enachman@...vell.com>
To: <gregory.clement@...tlin.com>, <andi.shyti@...nel.org>,
        <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <enachman@...vell.com>
Subject: [PATCH] i2c: mv64xxx: prevent illegal pointer access

From: Elad Nachman <enachman@...vell.com>

Spurious interrupts left while i2c controller still
at RX or TX state would try to access the RX or TX
buffer pointer, which is NULL.
Add check to verify buffer pointer is not NULL before
reading or writing the buffer for additional TX or RX
operations.

Signed-off-by: Elad Nachman <enachman@...vell.com>
---
 drivers/i2c/busses/i2c-mv64xxx.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 8fc26a511320..e6baa9c520b4 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -390,14 +390,18 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 		break;
 
 	case MV64XXX_I2C_ACTION_SEND_DATA:
-		writel(drv_data->msg->buf[drv_data->byte_posn++],
-			drv_data->reg_base + drv_data->reg_offsets.data);
+		if (drv_data->msg && drv_data->msg->buf)
+			writel(drv_data->msg->buf[drv_data->byte_posn++],
+				drv_data->reg_base + drv_data->reg_offsets.data);
 		writel(drv_data->cntl_bits,
 			drv_data->reg_base + drv_data->reg_offsets.control);
 		break;
 
 	case MV64XXX_I2C_ACTION_RCV_DATA:
-		drv_data->msg->buf[drv_data->byte_posn++] =
+		if (drv_data->msg && drv_data->msg->buf)
+			drv_data->msg->buf[drv_data->byte_posn++] =
+				readl(drv_data->reg_base + drv_data->reg_offsets.data);
+		else
 			readl(drv_data->reg_base + drv_data->reg_offsets.data);
 		writel(drv_data->cntl_bits,
 			drv_data->reg_base + drv_data->reg_offsets.control);
-- 
2.25.1