CVE-2025-71285: net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels

MHI stack offers the 'auto_queue' feature, which allows the MHI stack to
auto queue the buffers for the RX path (DL channel). Though this feature
simplifies the client driver design, it introduces race between the client
drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback'
for the DL channel may get called before the client driver is fully probed.
This means, by the time the dl_callback gets called, the client driver's
structures might not be initialized, leading to NULL ptr dereference.

Currently, the drivers have to workaround this issue by initializing the
internal structures before calling mhi_prepare_for_transfer_autoqueue().
But even so, there is a chance that the client driver's internal code path
may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is
called, leading to similar NULL ptr dereference. This issue has been
reported on the Qcom X1E80100 CRD machines affecting boot.

So to properly fix all these races, drop the MHI 'auto_queue' feature
altogether and let the client driver (QRTR) manage the RX buffers manually.
In the QRTR driver, queue the RX buffers based on the ring length during
probe and recycle the buffers in 'dl_callback' once they are consumed. This
also warrants removing the setting of 'auto_queue' flag from controller
drivers.

Currently, this 'auto_queue' feature is only enabled for IPCR DL channel.
So only the QRTR client driver requires the modification.

The Linux kernel CVE team has assigned CVE-2025-71285 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.17 with commit 227fee5fc99eeb74d43bf68832f6d59d30ac07d8 and fixed in 6.18.17 with commit 7bdff9b9b0c65ac7105416fe3a40686832515e20
	Issue introduced in 5.17 with commit 227fee5fc99eeb74d43bf68832f6d59d30ac07d8 and fixed in 6.19.6 with commit 8c464e00e0754e016816b1860fa9592dcad80eb2
	Issue introduced in 5.17 with commit 227fee5fc99eeb74d43bf68832f6d59d30ac07d8 and fixed in 7.0 with commit 51731792a25cb312ca94cdccfa139eb46de1b2ef
	Issue introduced in 5.15.63 with commit c682fb70a7dfc25b848a4ff3a385b0471b470606

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-71285
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/accel/qaic/mhi_controller.c
	drivers/bus/mhi/host/pci_generic.c
	drivers/net/wireless/ath/ath11k/mhi.c
	drivers/net/wireless/ath/ath12k/mhi.c
	net/qrtr/mhi.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/7bdff9b9b0c65ac7105416fe3a40686832515e20
	https://git.kernel.org/stable/c/8c464e00e0754e016816b1860fa9592dcad80eb2
	https://git.kernel.org/stable/c/51731792a25cb312ca94cdccfa139eb46de1b2ef