CVE-2025-71285
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Race Condition in Linux Kernel MHI Auto-Queue Feature

Publication date: 2026-05-06

Last updated on: 2026-05-06

Assigner: 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.
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Meta Information
Published
2026-05-06
Last Modified
2026-05-06
Generated
2026-05-07
AI Q&A
2026-05-06
EPSS Evaluated
N/A
NVD
CVE-2025-71285
EUVD
EUVD-2025-209675
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
qualcomm qrtr *
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's MHI stack, specifically related to the 'auto_queue' feature for IPCR DL channels. The 'auto_queue' feature allows the MHI stack to automatically queue buffers for the RX path, simplifying client driver design. However, it introduces a race condition between the client drivers and the MHI stack. For example, the 'dl_callback' for the DL channel may be called before the client driver is fully initialized, potentially causing a NULL pointer dereference because the client driver's structures might not be ready.

To fix this, the 'auto_queue' feature was removed, requiring the client driver (QRTR) to manage RX buffers manually. This change prevents the race condition by having the QRTR driver queue RX buffers during probe and recycle them in 'dl_callback' after consumption.


How can this vulnerability impact me? :

The vulnerability can lead to a NULL pointer dereference in the Linux kernel, which may cause system instability or crashes, particularly on affected Qualcomm hardware (Qcom X1E80100 CRD machines). This could impact device availability or reliability during boot or operation.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, the MHI 'auto_queue' feature should be dropped for IPCR DL channels, allowing the QRTR client driver to manage RX buffers manually.

  • Remove the setting of the 'auto_queue' flag from controller drivers.
  • Modify the QRTR driver to queue RX buffers based on the ring length during probe.
  • Recycle the RX buffers in the 'dl_callback' once they are consumed.

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