linux-kernel - [PATCH v2 12/12] bus: mhi: core: Remove MHI event ring IRQ handlers when powering down

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Message-Id: <1604022723-34578-13-git-send-email-bbhatt@codeaurora.org>
Date:   Thu, 29 Oct 2020 18:52:03 -0700
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        Bhaumik Bhatt <bbhatt@...eaurora.org>
Subject: [PATCH v2 12/12] bus: mhi: core: Remove MHI event ring IRQ handlers when powering down

While powering down, the device may or may not acknowledge an MHI
RESET issued by host for a graceful shutdown scenario and end up
sending an incoming data packet after tasklets have been killed.
If a rogue device sends this interrupt for a data transfer event
ring update, it can result in a tasklet getting scheduled while a
clean up is ongoing or has completed and cause access to freed
memory leading to a NULL pointer exception. Remove the interrupt
handlers for MHI event rings early on to avoid this scenario.

Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
---
 drivers/bus/mhi/core/pm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index ffbf6f5..28e2b87 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -627,6 +627,7 @@ static void mhi_pm_sys_error_transition(struct mhi_controller *mhi_cntrl)
 	for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
 		if (mhi_event->offload_ev)
 			continue;
+		free_irq(mhi_cntrl->irq[mhi_event->irq], mhi_event);
 		tasklet_kill(&mhi_event->task);
 	}
 
@@ -1164,7 +1165,7 @@ void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
 	/* Wait for shutdown to complete */
 	flush_work(&mhi_cntrl->st_worker);
 
-	mhi_deinit_free_irq(mhi_cntrl);
+	free_irq(mhi_cntrl->irq[0], mhi_cntrl);
 
 	if (!mhi_cntrl->pre_init) {
 		/* Free all allocated resources */
-- 
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