As part of I3C driver probing sequence for particular device instance,
While adding to queue it is trying to access ibi variable of dev which is
not yet initialized causing "Unable to handle kernel read from unreadable
memory" resulting in kernel panic.

Below is the sequence where this issue happened.
1. During boot up sequence IBI is received at host  from the slave device
   before requesting for IBI, Usually will request IBI by calling
   i3c_device_request_ibi() during probe of slave driver.
2. Since master code trying to access IBI Variable for the particular
   device instance before actually it initialized by slave driver,
   due to this randomly accessing the address and causing kernel panic.
3. i3c_device_request_ibi() function invoked by the slave driver where
   dev->ibi = ibi; assigned as part of function call
   i3c_dev_request_ibi_locked().
4. But when IBI request sent by slave device, master code  trying to access
   this variable before its initialized due to this race condition
   situation kernel panic happened.

Fixes: dd3c52846d595 ("i3c: master: svc: Add Silvaco I3C master driver")
Cc: stable@vger.kernel.org
Signed-off-by: Manjunatha Venkatesh <manjunatha.venkatesh@nxp.com>
---
Changes since v3:
  - Description  updated typo "Fixes:"

 drivers/i3c/master/svc-i3c-master.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index d6057d8c7dec..98c4d2e5cd8d 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -534,8 +534,11 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
 	switch (ibitype) {
 	case SVC_I3C_MSTATUS_IBITYPE_IBI:
 		if (dev) {
-			i3c_master_queue_ibi(dev, master->ibi.tbq_slot);
-			master->ibi.tbq_slot = NULL;
+			data = i3c_dev_get_master_data(dev);
+			if (master->ibi.slots[data->ibi]) {
+				i3c_master_queue_ibi(dev, master->ibi.tbq_slot);
+				master->ibi.tbq_slot = NULL;
+			}
 		}
 		svc_i3c_master_emit_stop(master);
 		break;
-- 
2.46.1

On Wed, Mar 12, 2025 at 07:23:56PM +0530, Manjunatha Venkatesh wrote:
> As part of I3C driver probing sequence for particular device instance,
> While adding to queue it is trying to access ibi variable of dev which is
> not yet initialized causing "Unable to handle kernel read from unreadable
> memory" resulting in kernel panic.
>
> Below is the sequence where this issue happened.
> 1. During boot up sequence IBI is received at host  from the slave device
>    before requesting for IBI, Usually will request IBI by calling
>    i3c_device_request_ibi() during probe of slave driver.
> 2. Since master code trying to access IBI Variable for the particular
>    device instance before actually it initialized by slave driver,
>    due to this randomly accessing the address and causing kernel panic.
> 3. i3c_device_request_ibi() function invoked by the slave driver where
>    dev->ibi = ibi; assigned as part of function call
>    i3c_dev_request_ibi_locked().
> 4. But when IBI request sent by slave device, master code  trying to access
>    this variable before its initialized due to this race condition
>    situation kernel panic happened.
>
> Fixes: dd3c52846d595 ("i3c: master: svc: Add Silvaco I3C master driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Manjunatha Venkatesh <manjunatha.venkatesh@nxp.com>
> ---
> Changes since v3:
>   - Description  updated typo "Fixes:"
>
>  drivers/i3c/master/svc-i3c-master.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> index d6057d8c7dec..98c4d2e5cd8d 100644
> --- a/drivers/i3c/master/svc-i3c-master.c
> +++ b/drivers/i3c/master/svc-i3c-master.c
> @@ -534,8 +534,11 @@ static void svc_i3c_master_ibi_work(struct work_struct *work)
>  	switch (ibitype) {
>  	case SVC_I3C_MSTATUS_IBITYPE_IBI:
>  		if (dev) {
> -			i3c_master_queue_ibi(dev, master->ibi.tbq_slot);
> -			master->ibi.tbq_slot = NULL;
> +			data = i3c_dev_get_master_data(dev);
> +			if (master->ibi.slots[data->ibi]) {
> +				i3c_master_queue_ibi(dev, master->ibi.tbq_slot);
> +				master->ibi.tbq_slot = NULL;
> +			}

You still not reply previous discussion:

https://lore.kernel.org/linux-i3c/Z8sOKZSjHeeP2mY5@lizhi-Precision-Tower-5810/T/#mfd02d6ddca0a4b57bc823dcbfa7571c564800417

This is not issue only at svc driver, which should be common problem for
other master controller drivers

Frank

>  		}
>  		svc_i3c_master_emit_stop(master);
>  		break;
> --
> 2.46.1
>