In the Linux kernel, the following vulnerability has been resolved:
cpufreq: intel_pstate: Fix NULL pointer dereference in update_cpu_qos_request()
The update_cpu_qos_request() function attempts to initialize the 'freq'
variable by dereferencing 'cpudata' before verifying if the 'policy'
is valid.
This issue occurs on systems booted with the "nosmt" parameter, where
all_cpu_data[cpu] is NULL for the SMT sibling threads. As a result,
any call to update_qos_requests() will result in a NULL pointer
dereference as the code will attempt to access pstate.turbo_freq using
the NULL cpudata pointer.
Also, pstate.turbo_freq may be updated by intel_pstate_get_hwp_cap()
after initializing the 'freq' variable, so it is better to defer the
'freq' until intel_pstate_get_hwp_cap() has been called.
Fix this by deferring the 'freq' assignment until after the policy and
driver_data have been validated.
[ rjw: Added one paragraph to the changelog ]