{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98022", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:19:56.069Z", "datePublished": "2026-09-25T10:23:42.116Z", "dateUpdated": "2026-10-19T09:12:27.416Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:12:27.416Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: cap tx_queue_len at S16_MAX to prevent oversized ring allocations\n\nSeveral subsystems allocate ring buffers sized by dev->tx_queue_len\nwith no upper bound. An unprivileged user (via unshare -Urn) can set a\nhuge tx_queue_len and exhaust global memory with ring allocations:\n\n- pfifo_fast: pfifo_fast_init() and pfifo_fast_change_tx_queue_len()\n allocate 3 skb_array rings of tx_queue_len entries each.\n- tun: tun_queue_resize() and the queue-attach path resize ptr_rings\n to tx_queue_len on the NETDEV_CHANGE_TX_QUEUE_LEN notifier.\n- tap (macvtap/ipvtap): tap_queue_resize() and tap_init() resize/init\n ptr_rings to tx_queue_len on the same notifier.\n\nnetif_change_tx_queue_len() is the single entry point for IFLA_TXQLEN,\nsysfs, and the SIOCSIFTXQLEN ioctl. Cap new_len at S16_MAX (32767)\nthere so the oversized value is rejected at set time. This takes\neffect whether the device is up or down, before dev->tx_queue_len is\nwritten, before any notifier fires, and before any ring is allocated.\nThe \"> S16_MAX\" check also subsumes the previous unsigned-long\ntruncation test, and a negative ifr_qlen from the ioctl lands far\nabove the cap after conversion, so both old failure modes are covered\nby the one comparison.\n\ntx_queue_len is ambigious: both a per-ring sizing multiplier and a\ndefault queue-length/limit knob for consumers that allocate\nnothing at set time (pfifo/bfifo/gred/plug/sfb limits, htb\ndirect_qlen, qfq max_classes, teql). 32767 is chosen as the largest\nvalue NLA_POLICY_FULL_RANGE can express for the u32 IFLA_TXQLEN\npolicy in patch 2/3 while staying a legitimate queue length on\nhigh-BDP paths; the ring-memory trade-off of a shared knob is\ndisclosed below.\n\nConditions to recreate the bug:\n- CONFIG_NET_SCHED=y, CONFIG_VETH=y, CONFIG_USER_NS=y, CONFIG_NET_NS=y.\n- Unprivileged user in a fresh user+net namespace (unshare -Urn).\n- pfifo_fast: create veth pairs, set tx_queue_len to 500000, attach\n mq+pfifo_fast. ~28 iterations OOMs a 2GB guest.\n- tun: create 50 tun devices with IFF_MULTI_QUEUE, set tx_queue_len to\n 500000, open 8 queues each. ~1.6GB of ptr_ring allocations OOMs a\n 512MB guest.\n- tap: same as tun with IFF_TAP. ~960MB OOMs a 512MB guest.\n- On the fixed kernel the oversized tx_queue_len is rejected with\n -ERANGE at set time (all four paths: RTM_SETLINK, RTM_NEWLINK\n create, sysfs, ioctl - the latter two via this check, the former\n two via this check and the 2/3 parse policy respectively)." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/dev.c" ], "versions": [ { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "24d02c909a1725ab9eceb92db7d02e4e841f17ca", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "5e5591a0f33f7c11bf1d338dbb6c5072575de64c", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "c8d4060610c69645733c92d94fceb4b93808ac4d", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "c2362c500931e5bd1826bce34e9ce28af80e7541", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "81c0e02076989743a603806a5a4f44d2c40dc01f", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "081340cf70a789b94b4174af54a63ffd49677a4e", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "a03b927bae4af5c23fd5315a237855c17cc8f422", "status": "affected", "versionType": "git" }, { "version": "6a643ddb5624be7e0694d49f5765a8d41c1ab6d0", "lessThan": "66ab4c59b74db7ab53a1c9083feaaede393a96a0", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/dev.c" ], "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.7", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "7.2.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/24d02c909a1725ab9eceb92db7d02e4e841f17ca" }, { "url": "https://git.kernel.org/stable/c/5e5591a0f33f7c11bf1d338dbb6c5072575de64c" }, { "url": "https://git.kernel.org/stable/c/c8d4060610c69645733c92d94fceb4b93808ac4d" }, { "url": "https://git.kernel.org/stable/c/c2362c500931e5bd1826bce34e9ce28af80e7541" }, { "url": "https://git.kernel.org/stable/c/81c0e02076989743a603806a5a4f44d2c40dc01f" }, { "url": "https://git.kernel.org/stable/c/081340cf70a789b94b4174af54a63ffd49677a4e" }, { "url": "https://git.kernel.org/stable/c/a03b927bae4af5c23fd5315a237855c17cc8f422" }, { "url": "https://git.kernel.org/stable/c/66ab4c59b74db7ab53a1c9083feaaede393a96a0" } ], "title": "net: cap tx_queue_len at S16_MAX to prevent oversized ring allocations", "x_generator": { "engine": "bippy-1.2.0" } } } }