Merge tag 'livepatching-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching

Pull livepatching updates from Petr Mladek:

 - Forced transitions block only to-be-removed livepatches [Chengming]

 - Detect when ftrace handler could not be disabled in self-tests [David]

 - Calm down warning from a static analyzer [Tom]

* tag 'livepatching-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
  livepatch: Reorder to use before freeing a pointer
  livepatch: Don't block removal of patches that are safe to unload
  livepatch: Skip livepatch tests if ftrace cannot be configured

Author: torvalds

kernel/livepatch/transition.c

@@ -641,6 +641,13 @@ void klp_force_transition(void)
 	for_each_possible_cpu(cpu)
 		klp_update_patch_state(idle_task(cpu));
 
-	klp_for_each_patch(patch)
-		patch->forced = true;
+	/* Set forced flag for patches being removed. */
+	if (klp_target_state == KLP_UNPATCHED)
+		klp_transition_patch->forced = true;
+	else if (klp_transition_patch->replace) {
+		klp_for_each_patch(patch) {
+			if (patch != klp_transition_patch)
+				patch->forced = true;
+		}
+	}
 }

samples/livepatch/livepatch-shadow-fix1.c

@@ -109,9 +109,9 @@ static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
 	void *d = obj;
 	int **shadow_leak = shadow_data;
 
-	kfree(*shadow_leak);
 	pr_info("%s: dummy @ %p, prevented leak @ %p\n",
 			 __func__, d, *shadow_leak);
+	kfree(*shadow_leak);
 }
 
 static void livepatch_fix1_dummy_free(struct dummy *d)

samples/livepatch/livepatch-shadow-fix2.c

@@ -61,9 +61,9 @@ static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data)
 	void *d = obj;
 	int **shadow_leak = shadow_data;
 
-	kfree(*shadow_leak);
 	pr_info("%s: dummy @ %p, prevented leak @ %p\n",
 			 __func__, d, *shadow_leak);
+	kfree(*shadow_leak);
 }
 
 static void livepatch_fix2_dummy_free(struct dummy *d)

tools/testing/selftests/livepatch/functions.sh

@@ -75,9 +75,25 @@ function set_dynamic_debug() {
 }
 
 function set_ftrace_enabled() {
-	result=$(sysctl -q kernel.ftrace_enabled="$1" 2>&1 && \
-		 sysctl kernel.ftrace_enabled 2>&1)
-	echo "livepatch: $result" > /dev/kmsg
+	local can_fail=0
+	if [[ "$1" == "--fail" ]] ; then
+		can_fail=1
+		shift
+	fi
+
+	local err=$(sysctl -q kernel.ftrace_enabled="$1" 2>&1)
+	local result=$(sysctl --values kernel.ftrace_enabled)
+
+	if [[ "$result" != "$1" ]] ; then
+		if [[ $can_fail -eq 1 ]] ; then
+			echo "livepatch: $err" > /dev/kmsg
+			return
+		fi
+
+		skip "failed to set kernel.ftrace_enabled = $1"
+	fi
+
+	echo "livepatch: kernel.ftrace_enabled = $result" > /dev/kmsg
 }
 
 function cleanup() {

tools/testing/selftests/livepatch/test-ftrace.sh

@@ -25,7 +25,8 @@ if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]]
 	die "livepatch kselftest(s) failed"
 fi
 
-set_ftrace_enabled 0
+# Check that ftrace could not get disabled when a livepatch is enabled
+set_ftrace_enabled --fail 0
 if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
 	echo -e "FAIL\n\n"
 	die "livepatch kselftest(s) failed"