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 <[email protected]>
---
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
On Mon, Jun 11, 2018 at 09:12:00PM -0400, Hugo Lefeuvre wrote:
> 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 <[email protected]>
We read the data from the user here and then we write it to the fifo
in pi433_write(). We should be using the device->tx_fifo_lock so that
we don't copy over the data at the same time we're writing it to the
fifo.
This bug could cause a user space program to fail.
regards,
dan carpenter
> We read the data from the user here and then we write it to the fifo
> in pi433_write(). We should be using the device->tx_fifo_lock so that
> we don't copy over the data at the same time we're writing it to the
> fifo.
Oh right, that makes the bug even worse.
In this case we don't even need to introduce a new lock, using
device->tx_fifo_lock should be fine. I'll update the patch.
--
Hugo Lefeuvre (hle) | http://www.owl.eu.com
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