[PATCH v2 1/1] i2c: mv64xxx: prevent illegal pointer access

[<enachman@marvell.com>]

From: Elad Nachman <enachman@marvell.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@marvell.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