cacheinfo: Check 'cache-unified' property to count cache leaves

The DeviceTree Specification v0.3 specifies that the cache node
'[d-|i-|]cache-size' property is required. The 'cache-unified'
property is specifies whether the cache level is separate
or unified.

If the cache-size property is missing, no cache leaves is accounted.
This can lead to a 'BUG: KASAN: slab-out-of-bounds' [1] bug.

Check 'cache-unified' property and always account for at least
one cache leaf when parsing the device tree.

[1] https://lore.kernel.org/all/0f19cb3f-d6cf-4032-66d2-dedc9d09a0e3@linaro.org/

Reported-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230104183033.755668-4-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 0a96d0b..9ad4403 100644 (file)
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -230,12 +230,9 @@ static int cache_setup_of_node(unsigned int cpu)
        return 0;
 }
 
-int init_of_cache_level(unsigned int cpu)
+static int of_count_cache_leaves(struct device_node *np)
 {
-       struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
-       struct device_node *np = of_cpu_device_node_get(cpu);
-       struct device_node *prev = NULL;
-       unsigned int levels = 0, leaves = 0, level;
+       unsigned int leaves = 0;
 
        if (of_property_read_bool(np, "cache-size"))
                ++leaves;
@@ -243,6 +240,28 @@ int init_of_cache_level(unsigned int cpu)
                ++leaves;
        if (of_property_read_bool(np, "d-cache-size"))
                ++leaves;
+
+       if (!leaves) {
+               /* The '[i-|d-|]cache-size' property is required, but
+                * if absent, fallback on the 'cache-unified' property.
+                */
+               if (of_property_read_bool(np, "cache-unified"))
+                       return 1;
+               else
+                       return 2;
+       }
+
+       return leaves;
+}
+
+int init_of_cache_level(unsigned int cpu)
+{
+       struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
+       struct device_node *np = of_cpu_device_node_get(cpu);
+       struct device_node *prev = NULL;
+       unsigned int levels = 0, leaves, level;
+
+       leaves = of_count_cache_leaves(np);
        if (leaves > 0)
                levels = 1;
 
@@ -256,12 +275,8 @@ int init_of_cache_level(unsigned int cpu)
                        goto err_out;
                if (level <= levels)
                        goto err_out;
-               if (of_property_read_bool(np, "cache-size"))
-                       ++leaves;
-               if (of_property_read_bool(np, "i-cache-size"))
-                       ++leaves;
-               if (of_property_read_bool(np, "d-cache-size"))
-                       ++leaves;
+
+               leaves += of_count_cache_leaves(np);
                levels = level;
        }