FAILED: patch "[PATCH] selinux: reject an unclaimed class value in" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 22b05fec62c0fe9864cfceb52f7d0f3a34d9b1dd
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026082040-morality-prudishly-7084@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 22b05fec62c0fe9864cfceb52f7d0f3a34d9b1dd Mon Sep 17 00:00:00 2001
From: Bryam Vargas <[email protected]>
Date: Fri, 31 Jul 2026 12:44:11 -0500
Subject: [PATCH] selinux: reject an unclaimed class value in
security_get_classes()

security_get_classes() sizes an array by p_classes.nprim and fills it at value - 1, so a class value the policy never defines leaves a NULL. sel_make_classes() passes every entry to sel_make_dir(), reaching the same d_alloc_name() dereference as the permission array. The class symbol table is allowed to be sparse (policydb_class_isvalid() exists to absorb that), but this getter builds its own array straight from the hash table and has no such predicate.

Fail the lookup when a value went unclaimed instead of handing out the NULL. Conforming policies define every class they declare and are unaffected.

index 90e81186cb2e..7afce975436e 100644
@@ -3304,6 +3304,7 @@ int security_get_classes(struct selinux_policy *policy,
 			 char ***classes, u32 *nclasses)
 {
 	struct policydb *policydb;
+	u32 i;
 	int rc;
 
 	policydb = &policy->policydb;

@@ -3316,16 +3317,29 @@ int security_get_classes(struct selinux_policy *policy,
 
 	rc = hashtab_map(&policydb->p_classes.table, get_classes_callback,
 			 *classes);
-	if (rc) {
-		u32 i;
+	if (rc)
+		goto err;
 
-		for (i = 0; i < *nclasses; i++)
-			kfree((*classes)[i]);
-		kfree(*classes);
+	/*
+	 * The class symtab may be sparse, which policydb_class_isvalid() exists
+	 * to absorb; the callback fills this array by value, so an unclaimed
+	 * one leaves a NULL that sel_make_classes() hands to sel_make_dir().
+	 */
+	for (i = 0; i < *nclasses; i++) {
+		if (!(*classes)[i]) {
+			rc = -EINVAL;
+			goto err;
+		}
 	}
 
 out:
 	return rc;
+
+err:
+	for (i = 0; i < *nclasses; i++)
+		kfree((*classes)[i]);
+	kfree(*classes);
+	return rc;
 }
 
 static int get_permissions_callback(void *k, void *d, void *args)