diff options
| author | George Cherian <george.cherian@cavium.com> | 2018-05-16 09:00:18 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-05-22 14:06:34 +0200 |
| commit | 88b4116e7e98454c2131094336e4f8861eebbd85 (patch) | |
| tree | 639eed4ee889c536ec063ae06bc76ca78948d6f9 /drivers/i2c | |
| parent | i2c: xlp9xx: Fix issue seen when updating receive length (diff) | |
| download | linux-88b4116e7e98454c2131094336e4f8861eebbd85.tar.xz linux-88b4116e7e98454c2131094336e4f8861eebbd85.zip | |
i2c: xlp9xx: Make sure the transfer size is not more than I2C_SMBUS_BLOCK_SIZE
For SMBus transactions the max permissible transfer size is
I2C_SMBUS_BLOCK_SIZE. It is possible that some clients might
not follow it strictly occasionally.
This would lead to stack corruption if the driver copies more than
I2C_SMBUS_BLOCK_SIZE bytes. Add a check to avoid such conditions.
Signed-off-by: Jayachandran C <jnair@caviumnetworks.com>
Signed-off-by: George Cherian <george.cherian@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-xlp9xx.c | 37 |
1 files changed, 24 insertions, 13 deletions
diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c index c268fde5bbd9..1f41a4f89c08 100644 --- a/drivers/i2c/busses/i2c-xlp9xx.c +++ b/drivers/i2c/busses/i2c-xlp9xx.c @@ -172,6 +172,8 @@ static void xlp9xx_i2c_update_rlen(struct xlp9xx_i2c_dev *priv) len = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_FIFOWCNT) & XLP9XX_I2C_FIFO_WCNT_MASK; len = max_t(u32, priv->msg_len, len + 4); + if (len >= I2C_SMBUS_BLOCK_MAX + 2) + return; val = (val & ~XLP9XX_I2C_CTRL_MCTLEN_MASK) | (len << XLP9XX_I2C_CTRL_MCTLEN_SHIFT); xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_CTRL, val); @@ -189,14 +191,20 @@ static void xlp9xx_i2c_drain_rx_fifo(struct xlp9xx_i2c_dev *priv) if (priv->len_recv) { /* read length byte */ rlen = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO); - *buf++ = rlen; - if (priv->client_pec) - ++rlen; - /* update remaining bytes and message length */ - priv->msg_buf_remaining = rlen; - priv->msg_len = rlen + 1; - priv->len_recv = false; + if (rlen > I2C_SMBUS_BLOCK_MAX || rlen == 0) { + rlen = 0; /*abort transfer */ + priv->msg_buf_remaining = 0; + priv->msg_len = 0; + } else { + *buf++ = rlen; + if (priv->client_pec) + ++rlen; /* account for error check byte */ + /* update remaining bytes and message length */ + priv->msg_buf_remaining = rlen; + priv->msg_len = rlen + 1; + } xlp9xx_i2c_update_rlen(priv); + priv->len_recv = false; } else { len = min(priv->msg_buf_remaining, len); for (i = 0; i < len; i++, buf++) @@ -315,10 +323,6 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg, xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_MFIFOCTRL, XLP9XX_I2C_MFIFOCTRL_RST); - /* set FIFO threshold if reading */ - if (priv->msg_read) - xlp9xx_i2c_update_rx_fifo_thres(priv); - /* set slave addr */ xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_SLAVEADDR, (msg->addr << XLP9XX_I2C_SLAVEADDR_ADDR_SHIFT) | @@ -337,9 +341,13 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg, val &= ~XLP9XX_I2C_CTRL_ADDMODE; priv->len_recv = msg->flags & I2C_M_RECV_LEN; - len = priv->len_recv ? XLP9XX_I2C_FIFO_SIZE : msg->len; + len = priv->len_recv ? I2C_SMBUS_BLOCK_MAX + 2 : msg->len; priv->client_pec = msg->flags & I2C_CLIENT_PEC; + /* set FIFO threshold if reading */ + if (priv->msg_read) + xlp9xx_i2c_update_rx_fifo_thres(priv); + /* set data length to be transferred */ val = (val & ~XLP9XX_I2C_CTRL_MCTLEN_MASK) | (len << XLP9XX_I2C_CTRL_MCTLEN_SHIFT); @@ -393,8 +401,11 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg, } /* update msg->len with actual received length */ - if (msg->flags & I2C_M_RECV_LEN) + if (msg->flags & I2C_M_RECV_LEN) { + if (!priv->msg_len) + return -EPROTO; msg->len = priv->msg_len; + } return 0; } |