5.4-stable review patch. If anyone has any objections, please let me know.
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From: Manjunatha Venkatesh manjunatha.venkatesh@nxp.com
commit bd496a44f041da9ef3afe14d1d6193d460424e91 upstream.
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 Link: https://lore.kernel.org/r/20250326123047.2797946-1-manjunatha.venkatesh@nxp.... Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/i3c/master.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -2198,6 +2198,9 @@ static void i3c_master_unregister_i3c_de */ 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->common.master->wq, &slot->work); }