i3c: Add NULL pointer check in i3c_master_queue_ibi()

[PATCH v6] i3c: Add NULL pointer check in i3c_master_queue_ibi()

Posted by Manjunatha Venkatesh 10 months, 2 weeks ago

The I3C master driver may receive an IBI from a target device that has not
been probed yet. In such cases, the master calls `i3c_master_queue_ibi()`
to queue an IBI work task, leading to "Unable to handle kernel read from
unreadable memory" and resulting in a kernel panic.

Typical IBI handling flow:
1. The I3C master scans target devices and probes their respective drivers.
2. The target device driver calls `i3c_device_request_ibi()` to enable IBI
   and assigns `dev->ibi = ibi`.
3. The I3C master receives an IBI from the target device and calls
   `i3c_master_queue_ibi()` to queue the target device driver’s IBI
   handler task.

However, since target device events are asynchronous to the I3C probe
sequence, step 3 may occur before step 2, causing `dev->ibi` to be `NULL`,
leading to a kernel panic.

Add a NULL pointer check in `i3c_master_queue_ibi()` to prevent accessing
an uninitialized `dev->ibi`, ensuring stability.

Fixes: 3a379bbcea0af ("i3c: Add core I3C infrastructure")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/Z9gjGYudiYyl3bSe@lizhi-Precision-Tower-5810/
Signed-off-by: Manjunatha Venkatesh <manjunatha.venkatesh@nxp.com>
---
Changes since v5:
  - Updated subject and commit message  with some more information.

 drivers/i3c/master.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index d5dc4180afbc..c65006aa0684 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -2561,6 +2561,9 @@ static void i3c_master_unregister_i3c_devs(struct i3c_master_controller *master)
  */
 void i3c_master_queue_ibi(struct i3c_dev_desc *dev, struct i3c_ibi_slot *slot)
 {
+	if (!dev->ibi || !slot)
+		return;
+
 	atomic_inc(&dev->ibi->pending_ibis);
 	queue_work(dev->ibi->wq, &slot->work);
 }
-- 
2.46.1

Re: [PATCH v6] i3c: Add NULL pointer check in i3c_master_queue_ibi()

Posted by Alexandre Belloni 10 months, 1 week ago

On Wed, 26 Mar 2025 18:00:46 +0530, Manjunatha Venkatesh wrote:
> The I3C master driver may receive an IBI from a target device that has not
> been probed yet. In such cases, the master calls `i3c_master_queue_ibi()`
> to queue an IBI work task, leading to "Unable to handle kernel read from
> unreadable memory" and resulting in a kernel panic.
> 
> Typical IBI handling flow:
> 1. The I3C master scans target devices and probes their respective drivers.
> 2. The target device driver calls `i3c_device_request_ibi()` to enable IBI
>    and assigns `dev->ibi = ibi`.
> 3. The I3C master receives an IBI from the target device and calls
>    `i3c_master_queue_ibi()` to queue the target device driver’s IBI
>    handler task.
> 
> [...]

Applied, thanks!

[1/1] i3c: Add NULL pointer check in i3c_master_queue_ibi()
      https://git.kernel.org/abelloni/c/bd496a44f041

Best regards,

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v6] i3c: Add NULL pointer check in i3c_master_queue_ibi()

Posted by Frank Li 10 months, 2 weeks ago

On Wed, Mar 26, 2025 at 06:00:46PM +0530, Manjunatha Venkatesh wrote:
> The I3C master driver may receive an IBI from a target device that has not
> been probed yet. In such cases, the master calls `i3c_master_queue_ibi()`
> to queue an IBI work task, leading to "Unable to handle kernel read from
> unreadable memory" and resulting in a kernel panic.
>
> Typical IBI handling flow:
> 1. The I3C master scans target devices and probes their respective drivers.
> 2. The target device driver calls `i3c_device_request_ibi()` to enable IBI
>    and assigns `dev->ibi = ibi`.
> 3. The I3C master receives an IBI from the target device and calls
>    `i3c_master_queue_ibi()` to queue the target device driver’s IBI
>    handler task.
>
> However, since target device events are asynchronous to the I3C probe
> sequence, step 3 may occur before step 2, causing `dev->ibi` to be `NULL`,
> leading to a kernel panic.
>
> Add a NULL pointer check in `i3c_master_queue_ibi()` to prevent accessing
> an uninitialized `dev->ibi`, ensuring stability.
>
> Fixes: 3a379bbcea0af ("i3c: Add core I3C infrastructure")
> Cc: stable@vger.kernel.org
> Link: https://lore.kernel.org/lkml/Z9gjGYudiYyl3bSe@lizhi-Precision-Tower-5810/
> Signed-off-by: Manjunatha Venkatesh <manjunatha.venkatesh@nxp.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> Changes since v5:
>   - Updated subject and commit message  with some more information.
>
>  drivers/i3c/master.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> index d5dc4180afbc..c65006aa0684 100644
> --- a/drivers/i3c/master.c
> +++ b/drivers/i3c/master.c
> @@ -2561,6 +2561,9 @@ static void i3c_master_unregister_i3c_devs(struct i3c_master_controller *master)
>   */
>  void i3c_master_queue_ibi(struct i3c_dev_desc *dev, struct i3c_ibi_slot *slot)
>  {
> +	if (!dev->ibi || !slot)
> +		return;
> +
>  	atomic_inc(&dev->ibi->pending_ibis);
>  	queue_work(dev->ibi->wq, &slot->work);
>  }
> --
> 2.46.1
>