CVE-2025-68232 — veth: more robust handing of race to avoid txq getting stuck

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

veth: more robust handing of race to avoid txq getting stuck

Commit dc82a33297fc ("veth: apply qdisc backpressure on full ptr_ring to reduce TX drops") introduced a race condition that can lead to a permanently stalled TXQ. This was observed in production on ARM64 systems (Ampere Altra Max).

The race occurs in veth_xmit(). The producer observes a full ptr_ring and stops the queue (netif_tx_stop_queue()). The subsequent conditional logic, intended to re-wake the queue if the consumer had just emptied it (if (__ptr_ring_empty(...)) netif_tx_wake_queue()), can fail. This leads to a "lost wakeup" where the TXQ remains stopped (QUEUE_STATE_DRV_XOFF) and traffic halts.

This failure is caused by an incorrect use of the __ptr_ring_empty() API from the producer side. As noted in kernel comments, this check is not guaranteed to be correct if a consumer is operating on another CPU. The empty test is based on ptr_ring->consumer_head, making it reliable only for the consumer. Using this check from the producer side is fundamentally racy.

This patch fixes the race by adopting the more robust logic from an earlier version V4 of the patchset, which always flushed the peer:

(1) In veth_xmit(), the racy conditional wake-up logic and its memory barrier are removed. Instead, after stopping the queue, we unconditionally call __veth_xdp_flush(rq). This guarantees that the NAPI consumer is scheduled, making it solely respons…

USN-8094-1 — linux, linux-aws, linux-aws-6.17, linux-gcp, linux-hwe-6.17, linux-oracle, linux-oracle-6.17 vulnerabilities

Affected: Ubuntu:24.04:LTS: linux-aws-6.17, Ubuntu:24.04:LTS: linux-hwe-6.17, Ubuntu:24.04:LTS: linux-oracle-6.17, Ubuntu:25.10: linux, Ubuntu:25.10: linux-aws, Ubuntu:25.10: linux-gcp, Ubuntu:25.10: linux-oracle

Qualys discovered that several vulnerabilities existed in the AppArmor Linux kernel Security Module (LSM). An unprivileged local attacker could use these issues to load, replace, and remove arbitrary AppArmor profiles causing denial of service, exposure of sensitive information (kernel memory), local privilege escalation, or possibly escape a container. (LP: #2143853)

It was discovered that some AMD Zen 5 processors supporting RDSEED instruction did not properly handle entropy, potentially resulting in the consumption of insufficiently random values. A local attacker could possibly use this issue to influence the values returned by the RDSEED instruction causing loss of confidentiality and integrity. (CVE-2025-62626)

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - Compute Acceleration Framework; - ATM drivers; - Network block device driver; - Bluetooth drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - Device frequency scaling framework; - Intel Stratix 10 firmware drivers; - GPIO subsystem; - GPU drivers; - Microsoft Hyper-V drivers; - CoreSight HW tracing drivers; - IIO subsystem; - InfiniBand drivers; - Input Device core drivers; - Input Device (Tablet) d…

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CVE-2025-68232 — veth: more robust handing of race to avoid txq getting stuck

USN-8094-1 — linux, linux-aws, linux-aws-6.17, linux-gcp, linux-hwe-6.17, linux-oracle, linux-oracle-6.17 vulnerabilities