Linux kernel trusted_keys: a failed TPM unseal can still instantiate the key when pcrlock succeeds

Impact

trusted_tpm_unseal() continued on to pcrlock() after the TPM unseal operation failed, and a successful pcrlock() return overwrote the unseal error, so key instantiation reported success. The consequence an operator cares about is that a trusted key whose TPM-sealed material could not actually be unsealed - the case sealing is meant to detect, a changed PCR state or a TPM error - is accepted instead of refused. Anything that relies on trusted keys as a measured-boot gate, such as unlocking encrypted local NVMe on a GPU node, loses the guarantee that the key only materialises on an unmodified boot. The record is a one-paragraph fix changelog with no attack scenario, no score and no CWE, so treat the exposure as stated and no wider.

Who can reach it

Local, on a system using trusted keys backed by a TPM with pcrlock. No remote path and no attacker-controlled input is described in the record; the flaw is an error path that fails open.

What to do

Take the stable kernel fix (return immediately when unseal fails) and reboot the node after draining GPU work. If you depend on trusted keys for a measured-boot decision, re-verify on a patched kernel that keys you expect to fail do fail. The record lists stable commits only, with no distro fixed versions.

References

Related entries

• Linux kernel keys: read method checked outside key->sem, so KEYCTL_READ can touch a freed key type moduleCVE-2026-99222 · Linux kernel keys (keyctl_read_key type method check outside key->sem)Unscored
• Linux kernel keys: keyring ordering leaks kernel addresses, defeating KASLR for a local userCVE-2026-99223 · Linux kernel keys (keyring associative-array index derived from kernel addresses)Unscored
• Linux kernel keys: NULL authorization payload dereferenced during a process keyring search, oopsing the hostCVE-2026-99225 · Linux kernel keys (request-key authorization payload in search_process_keyrings_rcu)Unscored
• ProFTPD mod_copy: unauthenticated SITE CPFR/CPTO gives arbitrary file read and writeCVE-2015-3306 · ProFTPD mod_copy (SITE CPFR / SITE CPTO)Critical
• Microsoft Hyper-V: vmswitch fails to validate guest OID requestsCVE-2021-28476 · Microsoft Hyper-VCritical
• Incus: instance snapshots bypass restricted.containers.lowlevel, giving command execution on the hostCVE-2026-48751 · Incus (instance snapshots ignore restricted.containers.lowlevel)Critical