Merge: CVE-2025-21785: arm64: cacheinfo: Avoid out-of-bounds write to cacheinfo array

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/6493

JIRA: https://issues.redhat.com/browse/RHEL-81666
CVE: CVE-2025-21785

```
commit 875d742
Author: Radu Rendec <rrendec@redhat.com>
Date:   Thu Feb 6 12:44:20 2025 -0500

    arm64: cacheinfo: Avoid out-of-bounds write to cacheinfo array

    The loop that detects/populates cache information already has a bounds
    check on the array size but does not account for cache levels with
    separate data/instructions cache. Fix this by incrementing the index
    for any populated leaf (instead of any populated level).

    Fixes: 5d425c1 ("arm64: kernel: add support for cpu cache information")

    Signed-off-by: Radu Rendec <rrendec@redhat.com>
    Link: https://lore.kernel.org/r/20250206174420.2178724-1-rrendec@redhat.com
    Signed-off-by: Will Deacon <will@kernel.org>```

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

---

<small>Created 2025-02-28 03:41 UTC by backporter - [KWF FAQ](https://red.ht/kernel_workflow_doc) - [Slack #team-kernel-workflow](https://redhat-internal.slack.com/archives/C04LRUPMJQ5) - [Source](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/webhook/utils/backporter.py) - [Documentation](https://gitlab.com/cki-project/kernel-workflow/-/blob/main/docs/README.backporter.md) - [Report an issue](https://gitlab.com/cki-project/kernel-workflow/-/issues/new?issue%5Btitle%5D=backporter%20webhook%20issue)</small>

Approved-by: Radu Rendec <rrendec@redhat.com>
Approved-by: Eric Chanudet <echanude@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Approved-by: Mark Langsdorf <mlangsdo@redhat.com>

Merged-by: Augusto Caringi <acaringi@redhat.com>

Author: caringi

arch/arm64/kernel/cacheinfo.c

@@ -101,16 +101,18 @@ int populate_cache_leaves(unsigned int cpu)
 	unsigned int level, idx;
 	enum cache_type type;
 	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
-	struct cacheinfo *this_leaf = this_cpu_ci->info_list;
+	struct cacheinfo *infos = this_cpu_ci->info_list;
 
 	for (idx = 0, level = 1; level <= this_cpu_ci->num_levels &&
-	     idx < this_cpu_ci->num_leaves; idx++, level++) {
+	     idx < this_cpu_ci->num_leaves; level++) {
 		type = get_cache_type(level);
 		if (type == CACHE_TYPE_SEPARATE) {
-			ci_leaf_init(this_leaf++, CACHE_TYPE_DATA, level);
-			ci_leaf_init(this_leaf++, CACHE_TYPE_INST, level);
+			if (idx + 1 >= this_cpu_ci->num_leaves)
+				break;
+			ci_leaf_init(&infos[idx++], CACHE_TYPE_DATA, level);
+			ci_leaf_init(&infos[idx++], CACHE_TYPE_INST, level);
 		} else {
-			ci_leaf_init(this_leaf++, type, level);
+			ci_leaf_init(&infos[idx++], type, level);
 		}
 	}
 	return 0;