{"id":"CVE-2026-64121","title":"net: ifb: report ethtool stats over num_tx_queues","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ifb: report ethtool stats over num_tx_queues\n\nifb_dev_init() allocates dp->tx_private to dev->num_tx_queues\nentries via kzalloc_objs(*txp, dev->num_tx_queues). Bot…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 6afdb8113cb007f9332f59a9b7fd45731b8a9de5","Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 16bd798cb6d8337d7c3eea1adc412f31b5181d5b","Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 301a554e458e2f5ec47f2c336a7cb03b877f9fd6","Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < f8a5a76b4a683043c6eff2a060bcaa17f9316ad5","Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4","Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 5db89c99566fc4728cc92e941d8e1975711e24b5","Linux 5.17"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:30:12.633352Z"},"published":"2026-07-19","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:34:26.335Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64121","references":[{"url":"https://git.kernel.org/stable/c/6afdb8113cb007f9332f59a9b7fd45731b8a9de5"},{"url":"https://git.kernel.org/stable/c/16bd798cb6d8337d7c3eea1adc412f31b5181d5b"},{"url":"https://git.kernel.org/stable/c/301a554e458e2f5ec47f2c336a7cb03b877f9fd6"},{"url":"https://git.kernel.org/stable/c/f8a5a76b4a683043c6eff2a060bcaa17f9316ad5"},{"url":"https://git.kernel.org/stable/c/2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4"},{"url":"https://git.kernel.org/stable/c/5db89c99566fc4728cc92e941d8e1975711e24b5"}],"tags":["cve.org"],"epss":0.00126,"epssPercentile":0.02286,"ingestedAt":"2026-11-06T16:57:43.234Z","slug":"CVE-2026-64121","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: ifb: report ethtool stats over num_tx_queues\n\nifb_dev_init() allocates dp->tx_private to dev->num_tx_queues\nentries via kzalloc_objs(*txp, dev->num_tx_queues). Both IFB\nper-queue RX and TX stats live in those entries: ifb_xmit() updates\ntxp->rx_stats using the skb queue mapping, ifb_ri_tasklet() updates\ntxp->tx_stats, and ifb_stats64() aggregates both over\ndev->num_tx_queues.\n\nThe ethtool stats callbacks instead size and walk the per-queue\nstats with dev->real_num_rx_queues and dev->real_num_tx_queues. With\nan asymmetric device where the RX queue count exceeds the TX queue\ncount, for example:\n\n    ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb\n    ethtool -S ifb10\n\nifb_get_ethtool_stats() indexes past the tx_private allocation and\ncopies adjacent slab data through ETHTOOL_GSTATS.\n\nUse dev->num_tx_queues consistently for the stats strings, the\nstats count, and the stats data walks. This reports one RX stats\ngroup and one TX stats group for each backing ifb_q_private entry,\nwhich is the queue set IFB can actually populate.\n\nReproduced under UML+KASAN at v7.1-rc2:\n\n  BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae\n  Read of size 8 at addr 0000000062dbd228 by task ethtool/36\n  ifb_fill_stats_data+0x3c/0xae\n  ifb_get_ethtool_stats+0xc0/0x129\n  __dev_ethtool+0x1ca5/0x363c\n  dev_ethtool+0x123/0x1b3\n  dev_ioctl+0x56c/0x744\n  sock_do_ioctl+0x15f/0x1b2\n  sock_ioctl+0x4d5/0x50a\n  sys_ioctl+0xd8b/0xde9\n\nWith the patch applied, the same UML+KASAN repro is silent and\nethtool -S ifb10 reports only the stats backed by the single\nallocated tx_private entry.\n\n## Affected\n\n- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 6afdb8113cb007f9332f59a9b7fd45731b8a9de5`\n- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 16bd798cb6d8337d7c3eea1adc412f31b5181d5b`\n- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 301a554e458e2f5ec47f2c336a7cb03b877f9fd6`\n- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < f8a5a76b4a683043c6eff2a060bcaa17f9316ad5`\n- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4`\n- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 5db89c99566fc4728cc92e941d8e1975711e24b5`\n- `Linux 5.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}