{"id":"CVE-2026-89763","summary":"KEYS: trusted: Fix TPM teardown ordering","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: trusted: Fix TPM teardown ordering\n\ntrusted_tpm_exit() drops the TPM chip reference and frees the digest\narray before unregistering the trusted key type. key_type_lookup()\nholds key_types_sem for reading until the key operation finishes, while\nunregister_key_type() takes it for writing. It therefore provides the\nsynchronization point that must precede backend teardown.\n\nThe current order permits this interleaving:\n\n  CPU 0                              CPU 1\n  trusted_tpm_exit()                 key_type_lookup(\"trusted\")\n    put_device(&chip-\u003edev)             trusted_tpm_seal()\n    kfree(digests)                       pcrlock()\n    unregister_key_type()                  tpm_pcr_extend(..., digests)\n\nCPU 1 can consequently dereference the freed digest array. The chip can\nalso be released before callbacks stop using it.\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in tpm_pcr_extend+0x1f0/0x200\n  Read of size 2 at addr ffff88810872d000 by task poc/89\n  Call Trace:\n    tpm_pcr_extend+0x1f0/0x200\n    pcrlock+0x42/0x70 [trusted]\n    trusted_tpm_seal+0x1b6/0x570 [trusted]\n    trusted_instantiate+0x293/0x340 [trusted]\n    __key_instantiate_and_link+0xb2/0x2b0\n    __key_create_or_update+0x61e/0xb50\n    __do_sys_add_key+0x1b8/0x310\n  Allocated by task 88:\n    __kmalloc_noprof+0x1a7/0x490\n    do_one_initcall+0xa1/0x390\n    do_init_module+0x2df/0x840\n  Freed by task 90:\n    kfree+0x131/0x3c0\n    trusted_tpm_exit+0x59/0xa0 [trusted]\n    __do_sys_delete_module+0x346/0x510\n\nMove unregister_key_type() before releasing either resource. This stops\nnew lookups and waits for in-flight key operations to finish before the\nbackend state is destroyed.","modified":"2026-09-13T03:47:20.673036613Z","published":"2026-09-11T19:47:04.352Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89763.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2f7541afbc57fe9d26769a22c31d8ce8790c9a19"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5e2d672280d97d83de43031d93761b12dadd7b8a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/753c978f2400f9783eb524842a975d3ac950d511"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89763.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89763"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0b6cf6b97b7ef1fa3c7fefab0cac897a1c4a3400"},{"fixed":"753c978f2400f9783eb524842a975d3ac950d511"},{"fixed":"2f7541afbc57fe9d26769a22c31d8ce8790c9a19"},{"fixed":"5e2d672280d97d83de43031d93761b12dadd7b8a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89763.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.1.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89763.json"}}],"schema_version":"1.9.0"}