On 3/6/2025 10:59 PM, Jeff Hugo wrote:
From: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
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.
Fixes: b89b6a863dd5 ("bus: mhi: host: Add spinlock to protect WP access when queueing TREs")
Signed-off-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
Signed-off-by: Jeff Hugo <jeff.hugo@xxxxxxxxxxxxxxxx>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@xxxxxxxxxxxxxxxx>
---
drivers/bus/mhi/host/main.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 4de75674f193..aa8a0ef697c7 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -1207,11 +1207,16 @@ 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;
@@ -1229,10 +1234,8 @@ 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);
@@ -1250,9 +1253,10 @@ 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,
