CVE-2026-64121

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