slub: fix leak of 'name' in sysfs_slab_add

Dave Jones

author

2014-03-06 21:11 UTC #0 lore raw

The failure paths of sysfs_slab_add don't release the allocation of 'name' made by create_unique_id() a few lines above the context of the diff below. Create a common exit path to make it more obvious what needs freeing.

Signed-off-by Dave Jones <[email protected]>

mm/slub.c +12 -9

index 25f14ad8f817..b2181d2682ac 100644
@@ -5197,17 +5197,13 @@ static int sysfs_slab_add(struct kmem_cache *s)
 
 	s->kobj.kset = slab_kset;
 	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
-	if (err) {
-		kobject_put(&s->kobj);
-		return err;
-	}
+	if (err)
+		goto err_out;
 
 	err = sysfs_create_group(&s->kobj, &slab_attr_group);
-	if (err) {
-		kobject_del(&s->kobj);
-		kobject_put(&s->kobj);
-		return err;
-	}
+	if (err)
+		goto err_sysfs;
+
 	kobject_uevent(&s->kobj, KOBJ_ADD);
 	if (!unmergeable) {
 		/* Setup first alias */

@@ -5215,6 +5211,13 @@ static int sysfs_slab_add(struct kmem_cache *s)
 		kfree(name);
 	}
 	return 0;
+
+err_sysfs:
+	kobject_del(&s->kobj);
+err_out:
+	kobject_put(&s->kobj);
+	kfree(name);
+	return err;
 }
 
 static void sysfs_slab_remove(struct kmem_cache *s)

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Vladimir Davydov

2014-03-07 06:18 UTC #1 lore raw

[adding Andrew to Cc]

Quoted 35 lines · Dave Jones

The failure paths of sysfs_slab_add don't release the allocation of 'name' made by create_unique_id() a few lines above the context of the diff below. Create a common exit path to make it more obvious what needs freeing.

Signed-off-by Dave Jones <[email protected]>

mm/slub.c +5 -9

index 25f14ad8f817..b2181d2682ac 100644
@@ -5197,17 +5197,13 @@ static int sysfs_slab_add(struct kmem_cache *s)
 
 	s->kobj.kset = slab_kset;
 	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
-	if (err) {
-		kobject_put(&s->kobj);
-		return err;
-	}
+	if (err)
+		goto err_out;
 
 	err = sysfs_create_group(&s->kobj, &slab_attr_group);
-	if (err) {
-		kobject_del(&s->kobj);
-		kobject_put(&s->kobj);
-		return err;
-	}
+	if (err)
+		goto err_sysfs;
+
 	kobject_uevent(&s->kobj, KOBJ_ADD);
 	if (!unmergeable) {
 		/* Setup first alias */

@@ -5215,6 +5211,13 @@ static int sysfs_slab_add(struct kmem_cache *s)
 		kfree(name);

mm/slub.c static int sysfs_slab_add(struct kmem_cache *s) · line 5221

Quoted 10 lines

mm/slub.c +7 -0

 	}
 	return 0;
+
+err_sysfs:
+	kobject_del(&s->kobj);
+err_out:
+	kobject_put(&s->kobj);
+	kfree(name);
+	return err;
 }

We should free the name only if !unmergeable, because:

sysfs_slab_add():

	if (unmergeable) {
		/*
		 * Slabcache can never be merged so we can use the name proper.
		 * This is typically the case for debug situations. In that
		 * case we can catch duplicate names easily.
		 */
		sysfs_remove_link(&slab_kset->kobj, s->name);
		name = s->name;
	} else {
		/*
		 * Create a unique name for the slab as a target
		 * for the symlinks.
		 */
		name = create_unique_id(s);
	}

Since this function was modified in the mmotm tree, I would propose something like this on top of mmotm to avoid further merge conflicts:

mm/slub.c +15 ~~-14~~

index c6eb29d65847..f4ca525c05b0 100644
@@ -5214,25 +5214,19 @@ static int sysfs_slab_add(struct kmem_cache *s)
 
 	s->kobj.kset = cache_kset(s);
 	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
-	if (err) {
-		kobject_put(&s->kobj);
-		return err;
-	}
+	if (err)
+		goto out_put_kobj;
 
 	err = sysfs_create_group(&s->kobj, &slab_attr_group);
-	if (err) {
-		kobject_del(&s->kobj);
-		kobject_put(&s->kobj);
-		return err;
-	}
+	if (err)
+		goto out_del_kobj;
 
 #ifdef CONFIG_MEMCG_KMEM
 	if (is_root_cache(s)) {
 		s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj);
 		if (!s->memcg_kset) {
-			kobject_del(&s->kobj);
-			kobject_put(&s->kobj);
-			return -ENOMEM;
+			err = -ENOMEM;
+			goto out_del_kobj;
 		}
 	}
 #endif

@@ -5241,9 +5235,16 @@ static int sysfs_slab_add(struct kmem_cache *s)
 	if (!unmergeable) {
 		/* Setup first alias */
 		sysfs_slab_alias(s, s->name);
-		kfree(name);
 	}
-	return 0;
+out:
+	if (!unmergeable)
+		kfree(name);
+	return err;
+out_del_kobj:
+	kobject_del(&s->kobj);
+out_put_kobj:
+	kobject_put(&s->kobj);
+	goto out;
 }
 
 static void sysfs_slab_remove(struct kmem_cache *s)

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Dave Jones

author

2014-03-07 15:33 UTC #2 lore raw

Quoted 7 lines · Vladimir Davydov

[adding Andrew to Cc]
Quoted 4 lines · Dave Jones
The failure paths of sysfs_slab_add don't release the allocation of 'name' made by create_unique_id() a few lines above the context of the diff below. Create a common exit path to make it more obvious what needs freeing.

Quoted 5 lines

Quoted 2 lines
Signed-off-by Dave Jones <[email protected]>
Since this function was modified in the mmotm tree, I would propose something like this on top of mmotm to avoid further merge conflicts:

Looks good to me.

thanks,

Dave

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>

Christoph Lameter

Acked-by

2014-03-07 17:14 UTC #3 lore raw

Quoted 4 lines · Dave Jones

Quoted 2 lines
Since this function was modified in the mmotm tree, I would propose something like this on top of mmotm to avoid further merge conflicts:
Looks good to me.

Acked-by Christoph Lameter <[email protected]>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>