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f5225a34bd
The mhi_ep_read_channel function incorrectly assumes the End of Transfer
(EOT) bit is present for each packet in a chained transactions, causing
it to advance mhi_chan->rd_offset beyond wr_offset during host-to-device
transfers when EOT has not yet arrived. This leads to access of unmapped
host memory, causing IOMMU faults and processing of stale TREs.
Modify the loop condition to ensure mhi_queue is not empty, allowing the
function to process only valid TREs up to the current write pointer to
prevent premature reads and ensure safe traversal of chained TREs.
Due to this change, buf_left needs to be removed from the while loop
condition to avoid exiting prematurely before reading the ring completely,
and also remove write_offset since it will always be zero because the new
cache buffer is allocated every time.
Fixes: 5301258899 ("bus: mhi: ep: Add support for reading from the host")
Co-developed-by: Akhil Vinod <akhil.vinod@oss.qualcomm.com>
Signed-off-by: Akhil Vinod <akhil.vinod@oss.qualcomm.com>
Signed-off-by: Sumit Kumar <sumit.kumar@oss.qualcomm.com>
[mani: reworded description slightly]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250910-final_chained-v3-1-ec77c9d88ace@oss.qualcomm.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.