From: Sumit Kumar sumk@qti.qualcomm.com
The current implementation of mhi_ep_read_channel, in case of chained transactions, assumes the End of Transfer(EOT) bit is received with the doorbell. As a result, it may incorrectly advance mhi_chan->rd_offset beyond wr_offset during host-to-device transfers when EOT has not yet arrived. This can lead to access of unmapped host memory, causing IOMMU faults and processing of stale TREs.
This change modifies the loop condition to ensure rd_offset remains behind wr_offset, allowing the function to process only valid TREs up to the current write pointer. This prevents premature reads and ensures safe traversal of chained TREs.
Fixes: 5301258899773 ("bus: mhi: ep: Add support for reading from the host") Cc: stable@vger.kernel.org Co-developed-by: Akhil Vinod akhvin@qti.qualcomm.com Signed-off-by: Akhil Vinod akhvin@qti.qualcomm.com Signed-off-by: Sumit Kumar sumk@qti.qualcomm.com --- drivers/bus/mhi/ep/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c index b3eafcf2a2c50d95e3efd3afb27038ecf55552a5..2e134f44952d1070c62c24aeca9effc7fd325860 100644 --- a/drivers/bus/mhi/ep/main.c +++ b/drivers/bus/mhi/ep/main.c @@ -468,7 +468,7 @@ static int mhi_ep_read_channel(struct mhi_ep_cntrl *mhi_cntrl,
mhi_chan->rd_offset = (mhi_chan->rd_offset + 1) % ring->ring_size; } - } while (buf_left && !tr_done); + } while (buf_left && !tr_done && mhi_chan->rd_offset != ring->wr_offset);
return 0;
--- base-commit: 4c06e63b92038fadb566b652ec3ec04e228931e8 change-id: 20250709-chained_transfer-0b95f8afa487
Best regards,