Commit 0686a818 authored by Jeff Hugo's avatar Jeff Hugo Committed by Manivannan Sadhasivam
Browse files

bus: mhi: host: Fix race between unprepare and queue_buf 



A client driver may use mhi_unprepare_from_transfer() to quiesce
incoming data during the client driver's tear down. The client driver
might also be processing data at the same time, resulting in a call to
mhi_queue_buf() which will invoke mhi_gen_tre(). If mhi_gen_tre() runs
after mhi_unprepare_from_transfer() has torn down the channel, a panic
will occur due to an invalid dereference leading to a page fault.

This occurs because mhi_gen_tre() does not verify the channel state
after locking it. Fix this by having mhi_gen_tre() confirm the channel
state is valid, or return error to avoid accessing deinitialized data.

Cc: stable@vger.kernel.org # 6.8
Fixes: b89b6a86 ("bus: mhi: host: Add spinlock to protect WP access when queueing TREs")
Signed-off-by: default avatarJeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: default avatarJeff Hugo <jeff.hugo@oss.qualcomm.com>
Reviewed-by: default avatarKrishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Reviewed-by: default avatarYoussef Samir <quic_yabdulra@quicinc.com>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: default avatarTroy Hanson <quic_thanson@quicinc.com>
Link: https://lore.kernel.org/r/20250306172913.856982-1-jeff.hugo@oss.qualcomm.com


[mani: added stable tag]
Signed-off-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
parent cba6bdfd

drivers/bus/mhi/host/main.c

+10 −6
Original line number Diff line number Diff line
@@ -1188,11 +1188,16 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, 
	struct mhi_ring_element *mhi_tre;

	struct mhi_buf_info *buf_info;

	int eot, eob, chain, bei;

	int ret;

	int ret = 0;



	/* Protect accesses for reading and incrementing WP */

	write_lock_bh(&mhi_chan->lock);



	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED) {

		ret = -ENODEV;

		goto out;

	}



	buf_ring = &mhi_chan->buf_ring;

	tre_ring = &mhi_chan->tre_ring;
@@ -1210,10 +1215,8 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, 


	if (!info->pre_mapped) {

		ret = mhi_cntrl->map_single(mhi_cntrl, buf_info);

		if (ret) {

			write_unlock_bh(&mhi_chan->lock);

			return ret;

		}

		if (ret)

			goto out;

	}



	eob = !!(flags & MHI_EOB);
@@ -1231,9 +1234,10 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, 
	mhi_add_ring_element(mhi_cntrl, tre_ring);

	mhi_add_ring_element(mhi_cntrl, buf_ring);



out:

	write_unlock_bh(&mhi_chan->lock);



	return 0;

	return ret;

}



int mhi_queue_buf(struct mhi_device *mhi_dev, enum dma_data_direction dir,