{"id":21685,"date":"2026-09-12T04:31:31","date_gmt":"2026-09-11T20:31:31","guid":{"rendered":"https:\/\/www.54iter.cn\/?vuln=cve-2026-89763"},"modified":"2026-09-12T04:31:31","modified_gmt":"2026-09-11T20:31:31","slug":"cve-2026-89763","status":"publish","type":"vuln","link":"https:\/\/www.54iter.cn\/?vuln=cve-2026-89763","title":{"rendered":"CVE-2026-89763 &#8211; In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: trusted: Fix TP"},"content":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>KEYS: trusted: Fix TPM teardown ordering<\/p>\n<p>trusted_tpm_exit() drops the TPM chip reference and frees the digest<br \/>\narray before unregistering the trusted key type. key_type_lookup()<br \/>\nholds key_types_sem for reading until the key operation finishes, while<br \/>\nunregister_key_type() takes it for writing. It therefore provides the<br \/>\nsynchronization point that must precede backend teardown.<\/p>\n<p>The current order permits this interleaving:<\/p>\n<p>  CPU 0                              CPU 1<br \/>\n  trusted_tpm_exit()                 key_type_lookup(&#8220;trusted&#8221;)<br \/>\n    put_device(&amp;chip-&gt;dev)             trusted_tpm_seal()<br \/>\n    kfree(digests)                       pcrlock()<br \/>\n    unregister_key_type()                  tpm_pcr_extend(&#8230;, digests)<\/p>\n<p>CPU 1 can consequently dereference the freed digest array. The chip can<br \/>\nalso be released before callbacks stop using it.<\/p>\n<p>KASAN reported:<\/p>\n<p>  BUG: KASAN: slab-use-after-free in tpm_pcr_extend+0x1f0\/0x200<br \/>\n  Read of size 2 at addr ffff88810872d000 by task poc\/89<br \/>\n  Call Trace:<br \/>\n    tpm_pcr_extend+0x1f0\/0x200<br \/>\n    pcrlock+0x42\/0x70 [trusted]<br \/>\n    trusted_tpm_seal+0x1b6\/0x570 [trusted]<br \/>\n    trusted_instantiate+0x293\/0x340 [trusted]<br \/>\n    __key_instantiate_and_link+0xb2\/0x2b0<br \/>\n    __key_create_or_update+0x61e\/0xb50<br \/>\n    __do_sys_add_key+0x1b8\/0x310<br \/>\n  Allocated by task 88:<br \/>\n    __kmalloc_noprof+0x1a7\/0x490<br \/>\n    do_one_initcall+0xa1\/0x390<br \/>\n    do_init_module+0x2df\/0x840<br \/>\n  Freed by task 90:<br \/>\n    kfree+0x131\/0x3c0<br \/>\n    trusted_tpm_exit+0x59\/0xa0 [trusted]<br \/>\n    __do_sys_delete_module+0x346\/0x510<\/p>\n<p>Move unregister_key_type() before releasing either resource. This stops<br \/>\nnew lookups and waits for in-flight key operations to finish before the<br \/>\nbackend state is destroyed.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the Linux kernel, the following vulnerability has been resolved:<\/p>\n<p>KEYS: trusted: Fix TPM teardown ordering<\/p>\n<p>trusted_tpm_exit() drops the TPM chip reference and frees the digest<br \/>\narray before unregis<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21685","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21685","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21685"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21685"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21685"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}