Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching

Pull livepatching updates from Jiri Kosina:
 "Fixes for selftests and samples for 'shadow variables' livepatching
  feature, from Petr Mladek"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
  livepatch: Handle allocation failure in the sample of shadow variable API
  livepatch/samples/selftest: Use klp_shadow_alloc() API correctly
  livepatch/selftest: Clean up shadow variable names and type
  livepatch/sample: Use the right type for the leaking data pointer

lib/livepatch/test_klp_shadow_vars.c

@@ -60,36 +60,43 @@ static int ptr_id(void *ptr)
  */
 static void *shadow_get(void *obj, unsigned long id)
 {
-	void *ret = klp_shadow_get(obj, id);
+	int **sv;
 
+	sv = klp_shadow_get(obj, id);
 	pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
-		__func__, ptr_id(obj), id, ptr_id(ret));
+		__func__, ptr_id(obj), id, ptr_id(sv));
 
-	return ret;
+	return sv;
 }
 
 static void *shadow_alloc(void *obj, unsigned long id, size_t size,
 			  gfp_t gfp_flags, klp_shadow_ctor_t ctor,
 			  void *ctor_data)
 {
-	void *ret = klp_shadow_alloc(obj, id, size, gfp_flags, ctor,
-				     ctor_data);
+	int **var = ctor_data;
+	int **sv;
+
+	sv = klp_shadow_alloc(obj, id, size, gfp_flags, ctor, var);
 	pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
 		__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
-		ptr_id(ctor_data), ptr_id(ret));
-	return ret;
+		ptr_id(*var), ptr_id(sv));
+
+	return sv;
 }
 
 static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
 				 gfp_t gfp_flags, klp_shadow_ctor_t ctor,
 				 void *ctor_data)
 {
-	void *ret = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor,
-					    ctor_data);
+	int **var = ctor_data;
+	int **sv;
+
+	sv = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor, var);
 	pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
 		__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
-		ptr_id(ctor_data), ptr_id(ret));
-	return ret;
+		ptr_id(*var), ptr_id(sv));
+
+	return sv;
 }
 
 static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
@@ -110,58 +117,70 @@ static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
 /* Shadow variable constructor - remember simple pointer data */
 static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
 {
-	int **shadow_int = shadow_data;
-	*shadow_int = ctor_data;
+	int **sv = shadow_data;
+	int **var = ctor_data;
+
+	if (!var)
+		return -EINVAL;
+
+	*sv = *var;
 	pr_info("%s: PTR%d -> PTR%d\n",
-		__func__, ptr_id(shadow_int), ptr_id(ctor_data));
+		__func__, ptr_id(sv), ptr_id(*var));
 
 	return 0;
 }
 
 static void shadow_dtor(void *obj, void *shadow_data)
 {
+	int **sv = shadow_data;
+
 	pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
-		__func__, ptr_id(obj), ptr_id(shadow_data));
+		__func__, ptr_id(obj), ptr_id(sv));
 }
 
 static int test_klp_shadow_vars_init(void)
 {
 	void *obj			= THIS_MODULE;
 	int id			= 0x1234;
-	size_t size		= sizeof(int *);
 	gfp_t gfp_flags		= GFP_KERNEL;
 
 	int var1, var2, var3, var4;
+	int *pv1, *pv2, *pv3, *pv4;
 	int **sv1, **sv2, **sv3, **sv4;
 
-	void *ret;
+	int **sv;
+
+	pv1 = &var1;
+	pv2 = &var2;
+	pv3 = &var3;
+	pv4 = &var4;
 
 	ptr_id(NULL);
-	ptr_id(&var1);
-	ptr_id(&var2);
-	ptr_id(&var3);
-	ptr_id(&var4);
+	ptr_id(pv1);
+	ptr_id(pv2);
+	ptr_id(pv3);
+	ptr_id(pv4);
 
 	/*
 	 * With an empty shadow variable hash table, expect not to find
 	 * any matches.
 	 */
-	ret = shadow_get(obj, id);
-	if (!ret)
+	sv = shadow_get(obj, id);
+	if (!sv)
 		pr_info("  got expected NULL result\n");
 
 	/*
 	 * Allocate a few shadow variables with different <obj> and <id>.
 	 */
-	sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1);
+	sv1 = shadow_alloc(obj, id, sizeof(pv1), gfp_flags, shadow_ctor, &pv1);
 	if (!sv1)
 		return -ENOMEM;
 
-	sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2);
+	sv2 = shadow_alloc(obj + 1, id, sizeof(pv2), gfp_flags, shadow_ctor, &pv2);
 	if (!sv2)
 		return -ENOMEM;
 
-	sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3);
+	sv3 = shadow_alloc(obj, id + 1, sizeof(pv3), gfp_flags, shadow_ctor, &pv3);
 	if (!sv3)
 		return -ENOMEM;
 
@@ -169,23 +188,23 @@ static int test_klp_shadow_vars_init(void)
 	 * Verify we can find our new shadow variables and that they point
 	 * to expected data.
 	 */
-	ret = shadow_get(obj, id);
-	if (!ret)
+	sv = shadow_get(obj, id);
+	if (!sv)
 		return -EINVAL;
-	if (ret == sv1 && *sv1 == &var1)
+	if (sv == sv1 && *sv1 == pv1)
 		pr_info("  got expected PTR%d -> PTR%d result\n",
 			ptr_id(sv1), ptr_id(*sv1));
 
-	ret = shadow_get(obj + 1, id);
-	if (!ret)
+	sv = shadow_get(obj + 1, id);
+	if (!sv)
 		return -EINVAL;
-	if (ret == sv2 && *sv2 == &var2)
+	if (sv == sv2 && *sv2 == pv2)
 		pr_info("  got expected PTR%d -> PTR%d result\n",
 			ptr_id(sv2), ptr_id(*sv2));
-	ret = shadow_get(obj, id + 1);
-	if (!ret)
+	sv = shadow_get(obj, id + 1);
+	if (!sv)
 		return -EINVAL;
-	if (ret == sv3 && *sv3 == &var3)
+	if (sv == sv3 && *sv3 == pv3)
 		pr_info("  got expected PTR%d -> PTR%d result\n",
 			ptr_id(sv3), ptr_id(*sv3));
 
@@ -193,14 +212,14 @@ static int test_klp_shadow_vars_init(void)
 	 * Allocate or get a few more, this time with the same <obj>, <id>.
 	 * The second invocation should return the same shadow var.
 	 */
-	sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
+	sv4 = shadow_get_or_alloc(obj + 2, id, sizeof(pv4), gfp_flags, shadow_ctor, &pv4);
 	if (!sv4)
 		return -ENOMEM;
 
-	ret = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
-	if (!ret)
+	sv = shadow_get_or_alloc(obj + 2, id, sizeof(pv4), gfp_flags, shadow_ctor, &pv4);
+	if (!sv)
 		return -EINVAL;
-	if (ret == sv4 && *sv4 == &var4)
+	if (sv == sv4 && *sv4 == pv4)
 		pr_info("  got expected PTR%d -> PTR%d result\n",
 			ptr_id(sv4), ptr_id(*sv4));
 
@@ -209,27 +228,27 @@ static int test_klp_shadow_vars_init(void)
 	 * longer find them.
 	 */
 	shadow_free(obj, id, shadow_dtor);			/* sv1 */
-	ret = shadow_get(obj, id);
-	if (!ret)
+	sv = shadow_get(obj, id);
+	if (!sv)
 		pr_info("  got expected NULL result\n");
 
 	shadow_free(obj + 1, id, shadow_dtor);			/* sv2 */
-	ret = shadow_get(obj + 1, id);
-	if (!ret)
+	sv = shadow_get(obj + 1, id);
+	if (!sv)
 		pr_info("  got expected NULL result\n");
 
 	shadow_free(obj + 2, id, shadow_dtor);			/* sv4 */
-	ret = shadow_get(obj + 2, id);
-	if (!ret)
+	sv = shadow_get(obj + 2, id);
+	if (!sv)
 		pr_info("  got expected NULL result\n");
 
 	/*
 	 * We should still find an <id+1> variable.
 	 */
-	ret = shadow_get(obj, id + 1);
-	if (!ret)
+	sv = shadow_get(obj, id + 1);
+	if (!sv)
 		return -EINVAL;
-	if (ret == sv3 && *sv3 == &var3)
+	if (sv == sv3 && *sv3 == pv3)
 		pr_info("  got expected PTR%d -> PTR%d result\n",
 			ptr_id(sv3), ptr_id(*sv3));
 
@@ -237,8 +256,8 @@ static int test_klp_shadow_vars_init(void)
 	 * Free all the <id+1> variables, too.
 	 */
 	shadow_free_all(id + 1, shadow_dtor);			/* sv3 */
-	ret = shadow_get(obj, id);
-	if (!ret)
+	sv = shadow_get(obj, id);
+	if (!sv)
 		pr_info("  shadow_get() got expected NULL result\n");
 
 

samples/livepatch/livepatch-shadow-fix1.c

@@ -52,17 +52,21 @@ struct dummy {
  */
 static int shadow_leak_ctor(void *obj, void *shadow_data, void *ctor_data)
 {
-	void **shadow_leak = shadow_data;
-	void *leak = ctor_data;
+	int **shadow_leak = shadow_data;
+	int **leak = ctor_data;
 
-	*shadow_leak = leak;
+	if (!ctor_data)
+		return -EINVAL;
+
+	*shadow_leak = *leak;
 	return 0;
 }
 
 static struct dummy *livepatch_fix1_dummy_alloc(void)
 {
 	struct dummy *d;
-	void *leak;
+	int *leak;
+	int **shadow_leak;
 
 	d = kzalloc(sizeof(*d), GFP_KERNEL);
 	if (!d)
@@ -76,25 +80,34 @@ static struct dummy *livepatch_fix1_dummy_alloc(void)
 	 * variable.  A patched dummy_free routine can later fetch this
 	 * pointer to handle resource release.
 	 */
-	leak = kzalloc(sizeof(int), GFP_KERNEL);
-	if (!leak) {
-		kfree(d);
-		return NULL;
+	leak = kzalloc(sizeof(*leak), GFP_KERNEL);
+	if (!leak)
+		goto err_leak;
+
+	shadow_leak = klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
+				       shadow_leak_ctor, &leak);
+	if (!shadow_leak) {
+		pr_err("%s: failed to allocate shadow variable for the leaking pointer: dummy @ %p, leak @ %p\n",
+		       __func__, d, leak);
+		goto err_shadow;
 	}
 
-	klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
-			 shadow_leak_ctor, leak);
-
 	pr_info("%s: dummy @ %p, expires @ %lx\n",
 		__func__, d, d->jiffies_expire);
 
 	return d;
+
+err_shadow:
+	kfree(leak);
+err_leak:
+	kfree(d);
+	return NULL;
 }
 
 static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
 {
 	void *d = obj;
-	void **shadow_leak = shadow_data;
+	int **shadow_leak = shadow_data;
 
 	kfree(*shadow_leak);
 	pr_info("%s: dummy @ %p, prevented leak @ %p\n",
@@ -103,7 +116,7 @@ static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
 
 static void livepatch_fix1_dummy_free(struct dummy *d)
 {
-	void **shadow_leak;
+	int **shadow_leak;
 
 	/*
 	 * Patch: fetch the saved SV_LEAK shadow variable, detach and

samples/livepatch/livepatch-shadow-fix2.c

@@ -59,7 +59,7 @@ static bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies)
 static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data)
 {
 	void *d = obj;
-	void **shadow_leak = shadow_data;
+	int **shadow_leak = shadow_data;
 
 	kfree(*shadow_leak);
 	pr_info("%s: dummy @ %p, prevented leak @ %p\n",
@@ -68,7 +68,7 @@ static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data)
 
 static void livepatch_fix2_dummy_free(struct dummy *d)
 {
-	void **shadow_leak;
+	int **shadow_leak;
 	int *shadow_count;
 
 	/* Patch: copy the memory leak patch from the fix1 module. */

samples/livepatch/livepatch-shadow-mod.c

@@ -95,7 +95,7 @@ struct dummy {
 static __used noinline struct dummy *dummy_alloc(void)
 {
 	struct dummy *d;
-	void *leak;
+	int *leak;
 
 	d = kzalloc(sizeof(*d), GFP_KERNEL);
 	if (!d)
@@ -105,7 +105,7 @@ static __used noinline struct dummy *dummy_alloc(void)
 		msecs_to_jiffies(1000 * EXPIRE_PERIOD);
 
 	/* Oops, forgot to save leak! */
-	leak = kzalloc(sizeof(int), GFP_KERNEL);
+	leak = kzalloc(sizeof(*leak), GFP_KERNEL);
 	if (!leak) {
 		kfree(d);
 		return NULL;