Medium [CVE-2026-68193] drop TXRX_NOTIFY on non-mmio buses
This medium-severity Red Hat Linux advisory covers CVE-2026-68193 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux for NVIDIA 26.
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Summary
In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7925: drop TXRX_NOTIFY on non-mmio buses PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7925_rx_check() and mt7925_queue_rx_skb() dispatch it to mt7925_mac_tx_free() on every bus. mt7925_mac_tx_free() cleans the DMA tx queues with mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup().
Only the mmio queue ops implement that callback; on USB it is NULL, so a TXRX_NOTIFY there calls a NULL pointer in the RX worker: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:0x0 Call Trace: mt7925_mac_tx_free+0x58/0x350 [mt7925_common] mt7925_rx_check+0xe2/0x130 [mt7925_common] mt76u_rx_worker+0x1b9/0x620 [mt76_usb] Drop the event on non-mmio buses via mt76_is_mmio(), as in commit 5683e1488aa9 ("wifi: mt76: connac: do not check WED status for non-mmio devices").
The mt7925 Wi-Fi driver incorrectly dispatches a memory-mapped I/O (MMIO) specific event to non-MMIO buses, such as USB. This improper handling leads to a NULL pointer dereference when attempting to clean up DMA transmit queues.
A remote attacker could exploit this vulnerability by sending specially crafted Wi-Fi packets, causing a system crash and resulting in a denial of service. MMIO-only TXRX_NOTIFY events are dispatched to mt7925_mac_tx_free(), calling unsupported queue ops.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 2 days ago·verify at source
- kernel-0:6.12.0-211.53.1.el10_2
- RHSA-2026:65334
Official advisory · high-confidence parse· fetched 2 days ago·verify at source
Mitigation checklist
- To mitigate this issue, prevent the mt7925e module from loading. See https://access.redhat.com/solutions/41278 for instructions.
Official advisory · high-confidence parse· fetched 2 days ago·verify at source
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