In the PI433_IOC_WR_TX_CFG case in pi433_ioctl, instance->tx_cfg is modified using copy_from_user(&instance->tx_cfg, argp, sizeof(struct pi433_tx_cfg))) without any kind of synchronization. In the case where two threads would execute this same command concurrently the tx_cfg field might enter in an inconsistent state. Add a mutex making sure that the PI433_IOC_WR_TX_CFG case will never be run by several threads concurrently. Signed-off-by: Hugo Lefeuvre <hle@owl.eu.com> --- drivers/staging/pi433/pi433_if.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c index d1e0ddbc79ce..94c9d5482f44 100644 --- a/drivers/staging/pi433/pi433_if.c +++ b/drivers/staging/pi433/pi433_if.c @@ -115,6 +115,7 @@ struct pi433_device { struct pi433_instance { struct pi433_device *device; + struct mutex tx_cfg_lock; /* guards race conditions when updating tx config */ struct pi433_tx_cfg tx_cfg; }; @@ -889,9 +890,13 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) return -EFAULT; break; case PI433_IOC_WR_TX_CFG: + mutex_lock(&instance->tx_cfg_lock); if (copy_from_user(&instance->tx_cfg, argp, - sizeof(struct pi433_tx_cfg))) + sizeof(struct pi433_tx_cfg))) { + mutex_unlock(&instance->tx_cfg_lock); return -EFAULT; + } + mutex_unlock(&instance->tx_cfg_lock); break; case PI433_IOC_RD_RX_CFG: if (copy_to_user(argp, &device->rx_cfg, @@ -966,6 +971,8 @@ static int pi433_open(struct inode *inode, struct file *filp) instance->tx_cfg.bit_rate = 4711; // TODO: fill instance->tx_cfg; + mutex_init(&instance->tx_cfg_lock); + /* instance data as context */ filp->private_data = instance; nonseekable_open(inode, filp); -- 2.17.1