CVE-2022-48997

In the Linux kernel, the following vulnerability has been resolved:

char: tpm: Protect tpm_pm_suspend with locks

Currently tpm transactions are executed unconditionally in tpm_pm_suspend() function, which may lead to races with other tpm accessors in the system.

Specifically, the hw_random tpm driver makes use of tpm_get_random(), and this function is called in a loop from a kthread, which means it's not frozen alongside userspace, and so can race with the work done during system suspend:

tpm tpm0: tpm_transmit: tpm_recv: error -52 tpm tpm0: invalid TPM_STS.x 0xff, dumping stack for forensics CPU: 0 PID: 1 Comm: init Not tainted 6.1.0-rc5+ #135 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-20220807_005459-localhost 04/01/2014 Call Trace: tpm_tis_status.cold+0x19/0x20 tpm_transmit+0x13b/0x390 tpm_transmit_cmd+0x20/0x80 tpm1_pm_suspend+0xa6/0x110 tpm_pm_suspend+0x53/0x80 __pnp_bus_suspend+0x35/0xe0 __device_suspend+0x10f/0x350

Fix this by calling tpm_try_get_ops(), which itself is a wrapper around tpm_chip_start(), but takes the appropriate mutex.

[Jason: reworked commit message, added metadata]

This issue is fixed in RHEL-9.2 and above (including 8.10):

in (rhel-9.3, rhel-9.4, rhel-9.5, rhel-9.6) char: tpm: Protect tpm_pm_suspend with locks
in (rhel-8.9, rhel-8.10) char: tpm: Protect tpm_pm_suspend with locks

Please note that while RHEL-9 kernel-rt still appears as affected, it has been fixed in the same RHSA as RHEL-9 kernel. This is because from RHEL-9.3 onwards, the kernel and kernel-rt fixes are bundled together in a single errata.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.