CVE-2026-31505 — iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

Affected: Linux

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

iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

iavf incorrectly uses real_num_tx_queues for ETH_SS_STATS. Since the value could change in runtime, we should use num_tx_queues instead.

Moreover iavf_get_ethtool_stats() uses num_active_queues while iavf_get_sset_count() and iavf_get_stat_strings() use real_num_tx_queues, which triggers out-of-bounds writes when we do "ethtool -L" and "ethtool -S" simultaneously [1].

For example when we change channels from 1 to 8, Thread 3 could be scheduled before Thread 2, and out-of-bounds writes could be triggered in Thread 3:

Thread 1 (ethtool -L) Thread 2 (work) Thread 3 (ethtool -S) iavf_set_channels() ... iavf_alloc_queues() -> num_active_queues = 8 iavf_schedule_finish_config() iavf_get_sset_count() real_num_tx_queues: 1 -> buffer for 1 queue iavf_get_ethtool_stats() num_active_queues: 8 -> out-of-bounds! iavf_finish_config() -> real_num_tx_queues = 8

Use immutable num_tx_queues in all related functions to avoid the issue.

[1] BUG: KASAN: vmalloc-out-of-bounds in iavf_add_one_etht…

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CVE-2026-31505 — iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()