Linux Kernel TOCTOU double-fetch in mana_hwc_rx_event_handler
CVE-2026-64034 Published on July 19, 2026
net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer
In the Linux kernel, the following vulnerability has been resolved:
net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer
In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from
DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp()
re-reads the same field from the same DMA buffer for test_bit() and
pointer arithmetic.
DMA-coherent memory is mapped uncacheable on x86 and is shared,
unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes
directly to host-visible memory. A H/W can modify the value
between the check and the use, bypassing the bounds validation.
Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a
stack-local variable in mana_hwc_rx_event_handler(), and passing the
validated value as a parameter to mana_hwc_handle_resp().
Products Associated with CVE-2026-64034
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Affected Versions
Linux:- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below a201c66edf2ebc6cfdc3813a889ba20fecebfae3 is affected.
- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below 70ad2dff8d052a85dfef15715b531f38a29108cf is affected.
- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below 566f42fb67a7ebfed6650e407e5b72e6b3e83bf7 is affected.
- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below 6180a06bbc99fd9114b8db4be6c4d46e40f046ef is affected.
- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below 09ec063d87c2dd3fa6f3561361a017bd882e9f37 is affected.
- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below 3c4db56ccd13dd020fbf43afabaee74a40ec75e4 is affected.
- Version ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and below 35f0f0a2536a4d604b4dbad92c85c4a8fdebb870 is affected.
- Version 5.13 is affected.
- Before 5.13 is unaffected.
- Version 5.15.209, <= 5.15.* is unaffected.
- Version 6.1.175, <= 6.1.* is unaffected.
- Version 6.6.142, <= 6.6.* is unaffected.
- Version 6.12.92, <= 6.12.* is unaffected.
- Version 6.18.34, <= 6.18.* is unaffected.
- Version 7.0.11, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.