[PATCH 4.19 244/338] ACPI: CPPC: Avoid out of bounds access when parsing _CPC data

Greg Kroah-Hartman
2022-04-14T13:49:00Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

commit 40d8abf364bcab23bc715a9221a3c8623956257b upstream.

If the NumEntries field in the _CPC return package is less than 2, do
not attempt to access the "Revision" element of that package, because
it may not be present then.

Fixes: 337aadff8e45 ("ACPI: Introduce CPU performance controls using CPPC")
BugLink: https://lore.kernel.org/lkml/20220322143534.GC32582@xsang-OptiPlex-9020/
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/acpi/cppc_acpi.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -742,6 +742,11 @@ int acpi_cppc_processor_probe(struct acp
cpc_obj = &out_obj->package.elements[0];
if (cpc_obj->type == ACPI_TYPE_INTEGER) {
num_ent = cpc_obj->integer.value;
+ if (num_ent <= 1) {
+ pr_debug("Unexpected _CPC NumEntries value (%d) for CPU:%d\n",
+ num_ent, pr->id);
+ goto out_free;
+ }
} else {
pr_debug("Unexpected entry type(%d) for NumEntries\n",
cpc_obj->type);