{"id":"CVE-2026-68138","revision":null,"records":[{"revision":"8c91b0359b9d447e82dfafba764be91f","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-68138","aliases":[],"title":"net/sched: serialize qdisc_rtab_list against concurrent get/put","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: serialize qdisc_rtab_list against concurrent get/put\n\nqdisc_get_rtab() and qdisc_put_rtab() mutate the process-global singly\nlinked list qdisc_rtab_list and a plain non-atomic 'int refcnt' with no\nlock. This was only safe because every caller historically held the RTNL\nmutex, which serialized all rate-table lookups, inserts and frees.\n\nThat invariant no longer holds. cls_flower sets\nTCF_PROTO_OPS_DOIT_UNLOCKED, so tc_new_tfilter() keeps rtnl_held == false\nfor it and sets TCA_ACT_FLAGS_NO_RTNL. That flag propagates through\ntcf_exts_validate_ex() -> tcf_action_init() -> tcf_action_init_1() ->\ntcf_police_init(), which calls qdisc_get_rtab()/qdisc_put_rtab() with the\nRTNL mutex NOT held. Two RTM_NEWTFILTER requests on different CPUs, each\nadding a flower filter with a police action carrying the same rate, then\nrace on qdisc_rtab_list and on the non-atomic refcnt, leading to a\nuse-after-free / double-free of the kmalloc-2k struct qdisc_rate_table.\nqdisc_rtab_list is a single global (not per-netns), so the corrupted\nobject is shared system-wide.\n\n BUG: KASAN: slab-use-after-free in qdisc_put_rtab+0x12f/0x160\n qdisc_put_rtab+0x12f/0x160\n tcf_police_init+0xda9/0x1590\n tcf_action_init_1+0x460/0x6b0\n tcf_action_init+0x439/0xa40\n tcf_exts_validate_ex+0x42d/0x550\n fl_change+0xddd/0x7da0\n tc_new_tfilter+0xaa7/0x2420\n rtnetlink_rcv_msg+0x95e/0xe90\n which belongs to the cache kmalloc-2k of size 2048\n\nProtect qdisc_rtab_list and the refcount with a dedicated spinlock. The\n(sleeping, GFP_KERNEL) allocation in qdisc_get_rtab() is performed before\ntaking the lock; if a concurrent inserter added an identical table in the\nmeantime the freshly allocated one is freed under the lock, so no\nduplicate is leaked. qdisc_put_rtab() now decrements the refcount and\nunlinks under the same lock.","state":0,"publishedAt":"2026-08-10T11:59:01.744+00:00","modifiedAt":"2026-10-19T20:58:52.975+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/sched/sch_api.c\"\n ],\n \"versions\": [\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"1b050d09dd1a0ddae83bf012cf4956b7a960235f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"6e0241f6cbb149d926ee8efee2c734fea71452cf\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"f93c89392bd3b180b5b7abc6fdae8e3dd667a313\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"4131dd0b6f67acddd616ed7c244e1d3eedd46e7b\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"d981098b76756ed71666a27518eeb69883657c43\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"8ddc2eb0d2da9c83f54f1e5720525b461b8480c4\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"fb29e1b41052488ee3f2d115d4a870497ebd7f7d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"470502de5bdb1ed0def643a4458593a40b8f6b66\",\n \"lessThan\": \"f43ee0c0730d6191629b5ee1ceae27b1ebfdc047\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/sched/sch_api.c\"\n ],\n \"versions\": [\n {\n \"version\": \"5.1\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"5.1\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.266\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.217\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.184\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.153\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.105\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.46\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1.6\",\n \"lessThanOrEqual\": \"7.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/1b050d09dd1a0ddae83bf012cf4956b7a960235f","https://git.kernel.org/stable/c/6e0241f6cbb149d926ee8efee2c734fea71452cf","https://git.kernel.org/stable/c/f93c89392bd3b180b5b7abc6fdae8e3dd667a313","https://git.kernel.org/stable/c/4131dd0b6f67acddd616ed7c244e1d3eedd46e7b","https://git.kernel.org/stable/c/d981098b76756ed71666a27518eeb69883657c43","https://git.kernel.org/stable/c/8ddc2eb0d2da9c83f54f1e5720525b461b8480c4","https://git.kernel.org/stable/c/fb29e1b41052488ee3f2d115d4a870497ebd7f7d","https://git.kernel.org/stable/c/f43ee0c0730d6191629b5ee1ceae27b1ebfdc047"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68138","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-68138","identifiers":["CVE-2026-68138"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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