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CVE-2026-64121

net: ifb: report ethtool stats over num_tx_queues

Published: 7/19/2026 Last updated: 7/19/2026 Reserved: 7/19/2026

In the Linux kernel, the following vulnerability has been resolved: net: ifb: report ethtool stats over num_tx_queues ifb_dev_init() allocates dp->tx_private to dev->num_tx_queues entries via kzalloc_objs(*txp, dev->num_tx_queues). Both IFB per-queue RX and TX stats live in those entries: ifb_xmit() updates txp->rx_stats using the skb queue mapping, ifb_ri_tasklet() updates txp->tx_stats, and ifb_stats64() aggregates both over dev->num_tx_queues. The ethtool stats callbacks instead size and walk the per-queue stats with dev->real_num_rx_queues and dev->real_num_tx_queues. With an asymmetric device where the RX queue count exceeds the TX queue count, for example: ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb ethtool -S ifb10 ifb_get_ethtool_stats() indexes past the tx_private allocation and copies adjacent slab data through ETHTOOL_GSTATS. Use dev->num_tx_queues consistently for the stats strings, the stats count, and the stats data walks. This reports one RX stats group and one TX stats group for each backing ifb_q_private entry, which is the queue set IFB can actually populate. Reproduced under UML+KASAN at v7.1-rc2: BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae Read of size 8 at addr 0000000062dbd228 by task ethtool/36 ifb_fill_stats_data+0x3c/0xae ifb_get_ethtool_stats+0xc0/0x129 __dev_ethtool+0x1ca5/0x363c dev_ethtool+0x123/0x1b3 dev_ioctl+0x56c/0x744 sock_do_ioctl+0x15f/0x1b2 sock_ioctl+0x4d5/0x50a sys_ioctl+0xd8b/0xde9 With the patch applied, the same UML+KASAN repro is silent and ethtool -S ifb10 reports only the stats backed by the single allocated tx_private entry.

CNA assigner: Linux (416baaa9-dc9f-4396-8d5f-8c081fb06d67) Requested by: n/a

Opam packages affected (29)

albatross cdrom conf-bpftool conf-libbpf conf-linux-libc-dev core core_unix hvsock mirage-block-unix mm ocaml-probes ortools_solvers orun rawlink rawlink-eio rawlink-lwt restricted shell solo5 solo5-bindings-hvt solo5-bindings-spt solo5-cross-aarch64 solo5-kernel-ukvm tracy-client tuntap uring vhd-format vhd-format-lwt xapi-stdext-unix

Products affected (2)

Product Vendor Version
Linux Linux n/a
Linux Linux < *

References (6)