{"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":"2026-10-03T11:01:40.664Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-03T11:01:40.664Z"},"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-rc3","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-rc3"}]}]}],"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"}}}}