CVE-2025-71285

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 drivers 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 drivers 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.

Weakness

The product dereferences a pointer that it expects to be valid but is NULL.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/51731792a25cb312ca94cdccfa139eb46de1b2ef
• https://git.kernel.org/stable/c/7bdff9b9b0c65ac7105416fe3a40686832515e20
• https://git.kernel.org/stable/c/8c464e00e0754e016816b1860fa9592dcad80eb2