{"id":"CVE-2026-43402","revision":"148e92b65c884168bda602dc47b3ee0a","records":[{"revision":"148e92b65c884168bda602dc47b3ee0a","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-43402","aliases":[],"title":"kthread: consolidate kthread exit paths to prevent use-after-free","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nkthread: consolidate kthread exit paths to prevent use-after-free\n\nGuillaume reported crashes via corrupted RCU callback function pointers\nduring KUnit testing. The crash was traced back to the pidfs rhashtable\nconversion which replaced the 24-byte rb_node with an 8-byte rhash_head\nin struct pid, shrinking it from 160 to 144 bytes.\n\nstruct kthread (without CONFIG_BLK_CGROUP) is also 144 bytes. With\nCONFIG_SLAB_MERGE_DEFAULT and SLAB_HWCACHE_ALIGN both round up to\n192 bytes and share the same slab cache. struct pid.rcu.func and\nstruct kthread.affinity_node both sit at offset 0x78.\n\nWhen a kthread exits via make_task_dead() it bypasses kthread_exit() and\nmisses the affinity_node cleanup. free_kthread_struct() frees the memory\nwhile the node is still linked into the global kthread_affinity_list. A\nsubsequent list_del() by another kthread writes through dangling list\npointers into the freed and reused memory, corrupting the pid's\nrcu.func pointer.\n\nInstead of patching free_kthread_struct() to handle the missed cleanup,\nconsolidate all kthread exit paths. Turn kthread_exit() into a macro\nthat calls do_exit() and add kthread_do_exit() which is called from\ndo_exit() for any task with PF_KTHREAD set. This guarantees that\nkthread-specific cleanup always happens regardless of the exit path -\nmake_task_dead(), direct do_exit(), or kthread_exit().\n\nReplace __to_kthread() with a new tsk_is_kthread() accessor in the\npublic header. Export do_exit() since module code using the\nkthread_exit() macro now needs it directly.","state":0,"publishedAt":"2026-05-08T14:21:43.55+00:00","modifiedAt":"2026-10-19T19:16:28.34+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                        \"include/linux/kthread.h\",\n                        \"kernel/exit.c\",\n                        \"kernel/kthread.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4d13f4304fa43471bfea101658a11feec7b28ac0\",\n                            \"lessThan\": \"4729c7b00a347fd37d0cbc265b85f2884c3e06b6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"4d13f4304fa43471bfea101658a11feec7b28ac0\",\n                            \"lessThan\": \"5a591d7a5e48d30100943940a30a6ab41b15c672\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"4d13f4304fa43471bfea101658a11feec7b28ac0\",\n                            \"lessThan\": \"28aaa9c39945b7925a1cc1d513c8f21ed38f5e4f\",\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                        \"include/linux/kthread.h\",\n                        \"kernel/exit.c\",\n                        \"kernel/kthread.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.14\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.14\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.19\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.9\",\n                            \"lessThanOrEqual\": \"6.19.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/4729c7b00a347fd37d0cbc265b85f2884c3e06b6","https://git.kernel.org/stable/c/5a591d7a5e48d30100943940a30a6ab41b15c672","https://git.kernel.org/stable/c/28aaa9c39945b7925a1cc1d513c8f21ed38f5e4f"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43402","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-43402","identifiers":["CVE-2026-43402"]},"retained":false,"historicalAffected":[]}],"coverage":[]}