From: Qiang Yu <quic_qianyu@xxxxxxxxxxx> commit 869a99907faea6d1835b0bd0d0422ae3519c6ea9 upstream. 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. Cc: stable@xxxxxxxxxxxxxxx # 5.19 Fixes: a6e2e3522f29 "bus: mhi: core: Add support for PM state transitions" Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx> Reviewed-by: Manivannan Sadhasivam <mani@xxxxxxxxxx> Link: https://lore.kernel.org/r/1665889532-13634-1-git-send-email-quic_qianyu@xxxxxxxxxxx [mani: CCed stable list] Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/bus/mhi/host/pm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- 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_cont 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); }
