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