On 17/03/2025 15:46:52+0000, Manjunatha Venkatesh wrote:
-----Original Message----- From: Frank Li frank.li@nxp.com Sent: Monday, March 17, 2025 6:57 PM To: Manjunatha Venkatesh manjunatha.venkatesh@nxp.com Cc: miquel.raynal@bootlin.com; conor.culhane@silvaco.com; alexandre.belloni@bootlin.com; linux-i3c@lists.infradead.org; linux- kernel@vger.kernel.org; stable@vger.kernel.org; rvmanjumce@gmail.com Subject: Re: [PATCH v4] svc-i3c-master: Fix read from unreadable memory at svc_i3c_master_ibi_work()
On Thu, Mar 13, 2025 at 05:15:42AM +0000, Manjunatha Venkatesh wrote:
-----Original Message----- From: Frank Li frank.li@nxp.com Sent: Wednesday, March 12, 2025 11:59 PM To: Manjunatha Venkatesh manjunatha.venkatesh@nxp.com Cc: miquel.raynal@bootlin.com; conor.culhane@silvaco.com; alexandre.belloni@bootlin.com; linux-i3c@lists.infradead.org; linux- kernel@vger.kernel.org; stable@vger.kernel.org; rvmanjumce@gmail.com Subject: Re: [PATCH v4] svc-i3c-master: Fix read from unreadable memory at svc_i3c_master_ibi_work()
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.
- 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.
- 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.
- 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().
- 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
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-T ower- 5810/T/#mfd02d6ddca0a4b57bc823dcbfa7571c564800417
[Manjunatha Venkatesh] : In the last mail answered to this question.
This is not issue only at svc driver, which should be common problem for other master controller drivers
[Manjunatha Venkatesh] :Yes, you are right. One of my project I3C interface is required, where we have used IMX board
as reference platform.
As part of boot sequence we come across this issue and tried to fix that
particular controller driver.
What is your conclusion on this? Is it not ok to take patch for SVC alone?
I perfer fix at common framwork to avoid every driver copy the similar logic code.
[Manjunatha Venkatesh] : As per your suggestion tried the below patch at common framework api i3c_master_queue_ibi() and looks working fine, didn't see any crash issue. if (!dev->ibi || !slot) { dev_warning("...");
Do we really need a warning, what would be the user action after seeing it?
return;} Will commit this change in next patch submission.
Frank
Frank
} svc_i3c_master_emit_stop(master); break;-- 2.46.1
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