There is a race condition where mhi_prepare_channel() updates the read and write pointers as the base address and in parallel, if an M0 transition occurs, the tasklet goes ahead and rings doorbells for all channels with a delta in TRE rings assuming they are already enabled. This causes a null pointer access. Fix it by adding a channel enabled check before ringing channel doorbells. Fixes: a6e2e3522f29 "bus: mhi: core: Add support for PM state transitions" Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx> --- v1->v2: add Fixes tags drivers/bus/mhi/host/pm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c index 4a42186..0834590 100644 --- a/drivers/bus/mhi/host/pm.c +++ b/drivers/bus/mhi/host/pm.c @@ -301,7 +301,8 @@ int mhi_pm_m0_transition(struct mhi_controller *mhi_cntrl) read_lock_irq(&mhi_chan->lock); /* Only ring DB if ring is not empty */ - if (tre_ring->base && tre_ring->wp != tre_ring->rp) + if (tre_ring->base && tre_ring->wp != tre_ring->rp && + mhi_chan->ch_state == MHI_CH_STATE_ENABLED) mhi_ring_chan_db(mhi_cntrl, mhi_chan); read_unlock_irq(&mhi_chan->lock); } -- 2.7.4
