CVE-2026-64034: net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

From: Greg Kroah-Hartman <[email protected]>

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

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().

The Linux kernel CVE team has assigned CVE-2026-64034 to this issue.


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

	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 5.15.209 with commit a201c66edf2ebc6cfdc3813a889ba20fecebfae3
	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 6.1.175 with commit 70ad2dff8d052a85dfef15715b531f38a29108cf
	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 6.6.142 with commit 566f42fb67a7ebfed6650e407e5b72e6b3e83bf7
	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 6.12.92 with commit 6180a06bbc99fd9114b8db4be6c4d46e40f046ef
	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 6.18.34 with commit 09ec063d87c2dd3fa6f3561361a017bd882e9f37
	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 7.0.11 with commit 3c4db56ccd13dd020fbf43afabaee74a40ec75e4
	Issue introduced in 5.13 with commit ca9c54d2d6a5ab2430c4eda364c77125d62e5e0f and fixed in 7.1 with commit 35f0f0a2536a4d604b4dbad92c85c4a8fdebb870

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-2026-64034
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/net/ethernet/microsoft/mana/hw_channel.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/a201c66edf2ebc6cfdc3813a889ba20fecebfae3
	https://git.kernel.org/stable/c/70ad2dff8d052a85dfef15715b531f38a29108cf
	https://git.kernel.org/stable/c/566f42fb67a7ebfed6650e407e5b72e6b3e83bf7
	https://git.kernel.org/stable/c/6180a06bbc99fd9114b8db4be6c4d46e40f046ef
	https://git.kernel.org/stable/c/09ec063d87c2dd3fa6f3561361a017bd882e9f37
	https://git.kernel.org/stable/c/3c4db56ccd13dd020fbf43afabaee74a40ec75e4
	https://git.kernel.org/stable/c/35f0f0a2536a4d604b4dbad92c85c4a8fdebb870