{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90058", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.784Z", "datePublished": "2026-09-17T16:05:43.184Z", "dateUpdated": "2026-10-19T08:57:15.626Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:57:15.626Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: bound qdisc_pkt_len to prevent qdisc soft lockup\n\nqdisc_get_stab() accepts a user-supplied size table, and\n__qdisc_calculate_pkt_len() amplifies qdisc_pkt_len() through the\noverhead, the size-table data (u16), and size_log (up to\nSTAB_SIZE_LOG_MAX). A crafted stab can therefore set qdisc_pkt_len()\nto ~1 GiB for an ordinary skb. Per-flow deficit schedulers such as\nDRR and ETS replenish one quantum per loop iteration; with a tiny\nquantum (1) they spin billions of times under the qdisc lock,\nproducing a soft lockup / RCU stall as illustrated by vega@nebusec.ai.\n\nCap the final qdisc_pkt_len() to QDISC_PKT_LEN_MAX so the size-table\namplification cannot drive deficit schedulers into an unbounded loop.\nA legitimate size table (e.g. qfq's overhead 999999999, which is\nhandled by dropping) is still accepted.\n\nIntroduce cap QDISC_PKT_LEN_MAX (1 << 20) = 1 MiB which is well above\nany legitimate single-skb wire length: the largest current skb->len\nis GSO_MAX_SIZE (524280), and an ATM-style size table (53/48 cell tax)\namplifies that to ~578 KB, both comfortably below 1 MiB. At the same\ntime, 1 MiB bounds the deficit refill loop to ~1M iterations per\npacket with quantum=1, which completes in a few milliseconds well\nunder the demonstrated softlockup threshold (~10^9 iterations).\n\nConditions to recreate the bug:\n- CONFIG_NET_SCHED=y, CONFIG_NET_SCH_DRR=y (or CONFIG_NET_SCH_ETS=y).\n- Attach a DRR (or ETS) root qdisc with a crafted TCA_STAB that\n amplifies qdisc_pkt_len to ~1 GiB (e.g. size_log=15, data=[32768]).\n- Add a class with a tiny quantum of 1 and send one small packet; the\n deficit loop spins billions of times under the qdisc lock and trips\n the softlockup detector (panic with kernel.softlockup_panic=1).\n- Reachable as root or from an unprivileged user in a fresh user+net\n namespace (unshare -Urn) with namespace-local CAP_NET_ADMIN." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/pkt_sched.h", "net/sched/sch_api.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4f0f4b09a95ef602fbdae948326beadd9c20eab3", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "0bc5a6280a132a2170c6fa742436e01b635f02de", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "448c34421b38ec7c93a0060a885218ca319d382b", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "82fdbf49b9f7528c82bf608cfa9710e5f81a198c", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "6e78792d8ce1fa3561713860ee8086901dde4f99", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1a5c26e586481bc82abc19ac92c3d9f10518f525", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "16d21a27df3f50b7251c9388fc5a7ab22703b469", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "8f735d64382dcf162f4276d6699d03ad2f859c0b", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/pkt_sched.h", "net/sched/sch_api.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.110", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "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": "2.6.12", "versionEndExcluding": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.221" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/4f0f4b09a95ef602fbdae948326beadd9c20eab3" }, { "url": "https://git.kernel.org/stable/c/0bc5a6280a132a2170c6fa742436e01b635f02de" }, { "url": "https://git.kernel.org/stable/c/448c34421b38ec7c93a0060a885218ca319d382b" }, { "url": "https://git.kernel.org/stable/c/82fdbf49b9f7528c82bf608cfa9710e5f81a198c" }, { "url": "https://git.kernel.org/stable/c/6e78792d8ce1fa3561713860ee8086901dde4f99" }, { "url": "https://git.kernel.org/stable/c/1a5c26e586481bc82abc19ac92c3d9f10518f525" }, { "url": "https://git.kernel.org/stable/c/16d21a27df3f50b7251c9388fc5a7ab22703b469" }, { "url": "https://git.kernel.org/stable/c/8f735d64382dcf162f4276d6699d03ad2f859c0b" } ], "title": "net/sched: bound qdisc_pkt_len to prevent qdisc soft lockup", "x_generator": { "engine": "bippy-1.2.0" } } } }