In the PI433_IOC_WR_TX_CFG case in pi433_ioctl, instance->tx_cfg is
modified via
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.
Additionally: if ioctl(PI433_IOC_WR_TX_CFG) and write() execute
concurrently the tx config might be modified while it is being
copied to the fifo, resulting in potential data corruption.
Fix: Get instance->tx_cfg_lock before modifying tx config in the
PI433_IOC_WR_TX_CFG case in pi433_ioctl.
Also, do not copy data directly from user space to instance->tx_cfg.
Instead use a temporary buffer allowing future checks for correctness
of copied data.
Signed-off-by: Hugo Lefeuvre <[email protected]>
---
Changes in v2:
- Use device->tx_fifo_lock instead of introducing a new lock in
instance.
- Do not copy data directly from user space to instance->tx_cfg,
instead use a temporary buffer allowing future checks for
correctness of copied data.
---
drivers/staging/pi433/pi433_if.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c
index b061f77dda41..3ec1ed01d04b 100644
--- a/drivers/staging/pi433/pi433_if.c
+++ b/drivers/staging/pi433/pi433_if.c
@@ -880,6 +880,7 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
int retval = 0;
struct pi433_instance *instance;
struct pi433_device *device;
+ struct pi433_tx_cfg tx_cfg_buffer;
void __user *argp = (void __user *)arg;
/* Check type and command number */
@@ -902,9 +903,15 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return -EFAULT;
break;
case PI433_IOC_WR_TX_CFG:
- if (copy_from_user(&instance->tx_cfg, argp,
- sizeof(struct pi433_tx_cfg)))
+ /* do not modify tx config while it is being copied to fifo */
+ mutex_lock(&device->tx_fifo_lock);
+ if (copy_from_user(&tx_cfg_buffer, argp,
+ sizeof(struct pi433_tx_cfg))) {
+ mutex_unlock(&device->tx_fifo_lock);
return -EFAULT;
+ }
+ memcpy(&instance->tx_cfg, &tx_cfg_buffer, sizeof(struct pi433_tx_cfg));
+ mutex_unlock(&device->tx_fifo_lock);
break;
case PI433_IOC_RD_RX_CFG:
if (copy_to_user(argp, &device->rx_cfg,
--
2.17.1
On Tue, Jun 12, 2018 at 09:47:41PM -0400, Hugo Lefeuvre wrote:
> In the PI433_IOC_WR_TX_CFG case in pi433_ioctl, instance->tx_cfg is
> modified via
>
> 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.
>
> Additionally: if ioctl(PI433_IOC_WR_TX_CFG) and write() execute
> concurrently the tx config might be modified while it is being
> copied to the fifo, resulting in potential data corruption.
>
> Fix: Get instance->tx_cfg_lock before modifying tx config in the
> PI433_IOC_WR_TX_CFG case in pi433_ioctl.
>
> Also, do not copy data directly from user space to instance->tx_cfg.
> Instead use a temporary buffer allowing future checks for correctness
> of copied data.
>
> Signed-off-by: Hugo Lefeuvre <[email protected]>
> ---
> Changes in v2:
> - Use device->tx_fifo_lock instead of introducing a new lock in
> instance.
> - Do not copy data directly from user space to instance->tx_cfg,
> instead use a temporary buffer allowing future checks for
> correctness of copied data.
> ---
> drivers/staging/pi433/pi433_if.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c
> index b061f77dda41..3ec1ed01d04b 100644
> --- a/drivers/staging/pi433/pi433_if.c
> +++ b/drivers/staging/pi433/pi433_if.c
> @@ -880,6 +880,7 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> int retval = 0;
> struct pi433_instance *instance;
> struct pi433_device *device;
> + struct pi433_tx_cfg tx_cfg_buffer;
> void __user *argp = (void __user *)arg;
>
> /* Check type and command number */
> @@ -902,9 +903,15 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return -EFAULT;
> break;
> case PI433_IOC_WR_TX_CFG:
> - if (copy_from_user(&instance->tx_cfg, argp,
> - sizeof(struct pi433_tx_cfg)))
> + /* do not modify tx config while it is being copied to fifo */
> + mutex_lock(&device->tx_fifo_lock);
> + if (copy_from_user(&tx_cfg_buffer, argp,
> + sizeof(struct pi433_tx_cfg))) {
> + mutex_unlock(&device->tx_fifo_lock);
> return -EFAULT;
> + }
> + memcpy(&instance->tx_cfg, &tx_cfg_buffer, sizeof(struct pi433_tx_cfg));
> + mutex_unlock(&device->tx_fifo_lock);
The lock is only needed around the memcpy() and that makes the code a
bit simpler as well.
regards,
dan carpenter
On Tue, Jun 12, 2018 at 09:47:41PM -0400, Hugo Lefeuvre wrote:
> drivers/staging/pi433/pi433_if.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c
> index b061f77dda41..3ec1ed01d04b 100644
> --- a/drivers/staging/pi433/pi433_if.c
> +++ b/drivers/staging/pi433/pi433_if.c
> @@ -880,6 +880,7 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> int retval = 0;
> struct pi433_instance *instance;
> struct pi433_device *device;
> + struct pi433_tx_cfg tx_cfg_buffer;
> void __user *argp = (void __user *)arg;
>
> /* Check type and command number */
> @@ -902,9 +903,15 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return -EFAULT;
> break;
> case PI433_IOC_WR_TX_CFG:
> - if (copy_from_user(&instance->tx_cfg, argp,
> - sizeof(struct pi433_tx_cfg)))
> + /* do not modify tx config while it is being copied to fifo */
There is no need for this comment, since it's obvious. Also if you use
simpler names then the copy fits on one line:
if (copy_from_user(&tx_cfg, argp, sizeof(tx_cfg)) {
> + mutex_lock(&device->tx_fifo_lock);
> + if (copy_from_user(&tx_cfg_buffer, argp,
> + sizeof(struct pi433_tx_cfg))) {
Sorry for the duplicate review, but it got sent to both my inboxes... :P
regards,
dan carpenter
Hi Dan,
> There is no need for this comment, since it's obvious. Also if you use
> simpler names then the copy fits on one line:
>
> if (copy_from_user(&tx_cfg, argp, sizeof(tx_cfg)) {
>
>
> > + mutex_lock(&device->tx_fifo_lock);
> > + if (copy_from_user(&tx_cfg_buffer, argp,
> > + sizeof(struct pi433_tx_cfg))) {
>
> Sorry for the duplicate review, but it got sent to both my inboxes... :P
Thanks for your review ! Patch updated.
Please tell me if you don't to be CC-ed anymore. :)
regards,
Hugo
--
Hugo Lefeuvre (hle) | http://www.owl.eu.com
4096/ 9C4F C8BF A4B0 8FC5 48EB 56B8 1962 765B B9A8 BACA