linux-kernel - [PATCH 1/1] mhi: Fix double dma free

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Message-Id: <20210210082538.2494-2-manivannan.sadhasivam@linaro.org>
Date:   Wed, 10 Feb 2021 13:55:38 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     hemantk@...eaurora.org, bbhatt@...eaurora.org,
        linux-arm-msm@...r.kernel.org, jhugo@...eaurora.org,
        linux-kernel@...r.kernel.org, loic.poulain@...aro.org,
        kvalo@...eaurora.org, ath11k@...ts.infradead.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH 1/1] mhi: Fix double dma free

From: Loic Poulain <loic.poulain@...aro.org>

mhi_deinit_chan_ctxt functionthat takes care of unitializing channel
resources, including unmapping coherent MHI areas, can be called
from different path in case of controller unregistering/removal:
 - From a client driver remove callback, via mhi_unprepare_channel
 - From mhi_driver_remove that unitialize all channels

mhi_driver_remove()
|-> driver->remove()
|    |-> mhi_unprepare_channel()
|        |-> mhi_deinit_chan_ctxt()
|...
|-> mhi_deinit_chan_ctxt()

This leads to double dma freeing...

Fix that by preventing deinit for already uninitialized channel.

Fixes: a7f422f2f89e ("bus: mhi: Fix channel close issue on driver remove")
Signed-off-by: Loic Poulain <loic.poulain@...aro.org>
Reported-by: Kalle Valo <kvalo@...eaurora.org>
Tested-by: Kalle Valo <kvalo@...eaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Link: https://lore.kernel.org/r/1612894264-15956-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/core/init.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index aa575d3fb3ae..be4eebb0971b 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -557,6 +557,9 @@ void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
 	tre_ring = &mhi_chan->tre_ring;
 	chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];
 
+	if (!chan_ctxt->rbase) /* Already uninitialized */
+		return;
+
 	mhi_free_coherent(mhi_cntrl, tre_ring->alloc_size,
 			  tre_ring->pre_aligned, tre_ring->dma_handle);
 	vfree(buf_ring->base);
-- 
2.25.1