1 files changed, 24 insertions, 4 deletions

diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
index ec299ae17a5a..917d54588d95 100644
--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -101,6 +101,7 @@ struct at91_twi_dev {
         unsigned twi_cwgr_reg;
         struct at91_twi_pdata *pdata;
         bool use_dma;
+        bool recv_len_abort;
         struct at91_twi_dma dma;
 };
 
@@ -267,12 +268,24 @@ static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
         *dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff;
         --dev->buf_len;
 
+        /* return if aborting, we only needed to read RHR to clear RXRDY*/
+        if (dev->recv_len_abort)
+                return;
+
         /* handle I2C_SMBUS_BLOCK_DATA */
         if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) {
-                dev->msg->flags &= ~I2C_M_RECV_LEN;
-                dev->buf_len += *dev->buf;
-                dev->msg->len = dev->buf_len + 1;
-                dev_dbg(dev->dev, "received block length %d\n", dev->buf_len);
+                /* ensure length byte is a valid value */
+                if (*dev->buf <= I2C_SMBUS_BLOCK_MAX && *dev->buf > 0) {
+                        dev->msg->flags &= ~I2C_M_RECV_LEN;
+                        dev->buf_len += *dev->buf;
+                        dev->msg->len = dev->buf_len + 1;
+                        dev_dbg(dev->dev, "received block length %d\n",
+                                         dev->buf_len);
+                } else {
+                        /* abort and send the stop by reading one more byte */
+                        dev->recv_len_abort = true;
+                        dev->buf_len = 1;
+                }
         }
 
         /* send stop if second but last byte has been read */
@@ -444,6 +457,12 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
                 ret = -EIO;
                 goto error;
         }
+        if (dev->recv_len_abort) {
+                dev_err(dev->dev, "invalid smbus block length recvd\n");
+                ret = -EPROTO;
+                goto error;
+        }
+
         dev_dbg(dev->dev, "transfer complete\n");
 
         return 0;
@@ -500,6 +519,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
         dev->buf_len = m_start->len;
         dev->buf = m_start->buf;
         dev->msg = m_start;
+        dev->recv_len_abort = false;
 
         ret = at91_do_twi_transfer(dev);