diff options
| -rw-r--r-- | drivers/i2c/i2c-dev.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index 45048323b75e..5ec2261574ec 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -265,19 +265,41 @@ static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client, res = 0; for (i = 0; i < rdwr_arg.nmsgs; i++) { - /* Limit the size of the message to a sane amount; - * and don't let length change either. */ - if ((rdwr_pa[i].len > 8192) || - (rdwr_pa[i].flags & I2C_M_RECV_LEN)) { + /* Limit the size of the message to a sane amount */ + if (rdwr_pa[i].len > 8192) { res = -EINVAL; break; } + data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf; rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len); if (IS_ERR(rdwr_pa[i].buf)) { res = PTR_ERR(rdwr_pa[i].buf); break; } + + /* + * If the message length is received from the slave (similar + * to SMBus block read), we must ensure that the buffer will + * be large enough to cope with a message length of + * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus + * drivers allow. The first byte in the buffer must be + * pre-filled with the number of extra bytes, which must be + * at least one to hold the message length, but can be + * greater (for example to account for a checksum byte at + * the end of the message.) + */ + if (rdwr_pa[i].flags & I2C_M_RECV_LEN) { + if (!(rdwr_pa[i].flags & I2C_M_RD) || + rdwr_pa[i].buf[0] < 1 || + rdwr_pa[i].len < rdwr_pa[i].buf[0] + + I2C_SMBUS_BLOCK_MAX) { + res = -EINVAL; + break; + } + + rdwr_pa[i].len = rdwr_pa[i].buf[0]; + } } if (res < 0) { int j; |