github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-22 12:44:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

cpufreq/amd-pstate: handle missing policy in dynamic EPP callbacks

Browse Source 
cpufreq_cpu_get() returns NULL when no cpufreq policy is associated with
the requested CPU, for example because the CPU is offline or the policy
has already been torn down.  Both amd_pstate_power_supply_notifier() and
amd_pstate_profile_set() acquire a policy via cpufreq_cpu_get() and then
pass that pointer to amd_pstate_get_balanced_epp() and
amd_pstate_set_epp(), which dereference it unconditionally.  A racing
CPU hotplug or driver teardown can therefore lead to a NULL pointer
dereference on either of these dynamic EPP paths.

The third cpufreq_cpu_get() caller in this file, amd_pstate_verify(),
already handles the NULL case.  Bring the two new callers in line with
that pattern: return NOTIFY_OK from the power-supply notifier (matching
the other "nothing to do" exits) and -ENODEV from amd_pstate_profile_set()
(the usual cpufreq error for a missing CPU policy).

Found by code inspection; not tested on hardware.

Fixes: e30ca6dd53 ("cpufreq/amd-pstate: Add dynamic energy performance preference")
Fixes: 798c47593c ("cpufreq/amd-pstate: Add support for platform profile class")
Signed-off-by: EDAMAMEX <edame8080@gmail.com>
Link: https://lore.kernel.org/r/20260520070211.2753183-1-edame8080@gmail.com
Signed-off-by: Mario Limonciello <superm1@kernel.org>
This commit is contained in:
EDAMAMEX 2026-05-20 16:02:11 +09:00 committed by Mario Limonciello
parent d0f4c1c8cb
commit 39c0cf62fc
1 changed files with 6 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/cpufreq/amd-pstate.c
View File

@ -1170,6 +1170,9 @@ static int amd_pstate_power_supply_notifier(struct notifier_block *nb,
if (cpudata->current_profile != PLATFORM_PROFILE_BALANCED)
return 0;
if (!policy)
return NOTIFY_OK;
epp = amd_pstate_get_balanced_epp(policy);
ret = amd_pstate_set_epp(policy, epp);
@ -1205,6 +1208,9 @@ static int amd_pstate_profile_set(struct device *dev,
struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpudata->cpu);
int ret;
if (!policy)
return -ENODEV;
switch (profile) {
case PLATFORM_PROFILE_LOW_POWER:
ret = amd_pstate_set_epp(policy, AMD_CPPC_EPP_POWERSAVE);