{"id":"CVE-2026-74583","revision":"9a0eb32a5a974b058054c334704cc733","records":[{"revision":"9a0eb32a5a974b058054c334704cc733","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-74583","aliases":[],"title":"net/sched: cls_route: fix fastmap use-after-free on filter","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: fix fastmap use-after-free on filter\n\nThe route4 classifier maintains a 16-slot fastmap cache that stores raw\nstruct route4_filter pointers indexed by (id, iif). The reader\n(route4_classify) populates this cache via route4_set_fastmap() for every\nclassified packet that hits a filter. The writer (route4_delete,\nroute4_change) clears the cache via route4_reset_fastmap() before\nRCU-deferred kfree of the filter.\n\nThis creates a UAF race:\n 1. Reader walks the RCU-protected bucket chain, finds filter f\n 2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()\n 3. Reader calls route4_set_fastmap() and writes f into the cache\n    *after* the writer's reset, caching a pointer about to be freed\n 4. After the RCU grace period, kfree(f) executes\n 5. Next classified packet on the same (id, iif) tuple hits the stale\n    fastmap entry and reads f->res from freed memory\n\nReproduced with an mdelay(100) accelerator in route4_set_fastmap() and a\nconcurrent add/delete stress test (provided by both zdi and Santosh).\nBoth triggered KASAN slab-use-after-free reports in the route4 fastmap\npaths.\n\nFix:\nIntroduce a per-filter boolean dying flag to suppress stale fastmap\nrepublishing by in-flight readers.","state":0,"publishedAt":"2026-08-21T16:31:55.886+00:00","modifiedAt":"2026-10-16T19:05:58.388+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/cls_route.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"7897198b26445b4009a057bda1986b94a99e5d5f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"820f083c294ad6d319c02a7d43294f2ed2565139\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"5ec9001be6d0eb527251125632ec8fe88278897f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"b969984b2bdc85d721ce4047cd270cd37ec705a2\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"a17f636c9330eac879822ce29f998e5abd1b72c1\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"0e7a8cf8895b06d07c7311f028eba16ad742b9bc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"ae9aff87025219005a2d16b4fe83d6f24643e50d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1109c00547fc66df45b9ff923544be4c1e1bec13\",\n                            \"lessThan\": \"47d7f7051253bdc02b1d245d87e38f16d31a74df\",\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/cls_route.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3.18\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"3.18\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.265\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.216\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.183\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.152\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.104\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.45\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.9\",\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/7897198b26445b4009a057bda1986b94a99e5d5f","https://git.kernel.org/stable/c/820f083c294ad6d319c02a7d43294f2ed2565139","https://git.kernel.org/stable/c/5ec9001be6d0eb527251125632ec8fe88278897f","https://git.kernel.org/stable/c/b969984b2bdc85d721ce4047cd270cd37ec705a2","https://git.kernel.org/stable/c/a17f636c9330eac879822ce29f998e5abd1b72c1","https://git.kernel.org/stable/c/0e7a8cf8895b06d07c7311f028eba16ad742b9bc","https://git.kernel.org/stable/c/ae9aff87025219005a2d16b4fe83d6f24643e50d","https://git.kernel.org/stable/c/47d7f7051253bdc02b1d245d87e38f16d31a74df"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74583","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-74583","identifiers":["CVE-2026-74583"]},"retained":false,"historicalAffected":[]}],"coverage":[]}