x86, pat: Fix memory leak in free_memtype

Reserve_memtype will allocate memory for new memtype, but
in free_memtype, after the memtype erased from rbtree, the
memory is not freed.

Changes since V1:
make rbt_memtype_erase return erased memtype so that
it can be freed in free_memtype.

[ hpa: not for -stable: 2.6.34 and earlier not affected ]

Signed-off-by: Xiaotian Feng <[e-mail]>
LKML-Reference: <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Venkatesh Pallipadi <[e-mail]>
Cc: Jack Steiner <[e-mail]>
Acked-by: Suresh Siddha <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/mm/pat.c

···
 {
 	int err = -EINVAL;
 	int is_range_ram;
+	struct memtype *entry;
 
 	if (!pat_enabled)
 		return 0;
···
 	}
 
 	spin_lock(&memtype_lock);
-	err = rbt_memtype_erase(start, end);
+	entry = rbt_memtype_erase(start, end);
 	spin_unlock(&memtype_lock);
 
-	if (err) {
+	if (!entry) {
 		printk(KERN_INFO "%s:%d freeing invalid memtype %Lx-%Lx\n",
 			current->comm, current->pid, start, end);
+		return -EINVAL;
 	}
+
+	kfree(entry);
 
 	dprintk("free_memtype request 0x%Lx-0x%Lx\n", start, end);
 
-	return err;
+	return 0;
 }
 
 

arch/x86/mm/pat_internal.h

···
 #ifdef CONFIG_X86_PAT
 extern int rbt_memtype_check_insert(struct memtype *new,
 					unsigned long *new_type);
-extern int rbt_memtype_erase(u64 start, u64 end);
+extern struct memtype *rbt_memtype_erase(u64 start, u64 end);
 extern struct memtype *rbt_memtype_lookup(u64 addr);
 extern int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos);
 #else
 static inline int rbt_memtype_check_insert(struct memtype *new,
 					unsigned long *new_type)
 { return 0; }
-static inline int rbt_memtype_erase(u64 start, u64 end)
-{ return 0; }
+static inline struct memtype *rbt_memtype_erase(u64 start, u64 end)
+{ return NULL; }
 static inline struct memtype *rbt_memtype_lookup(u64 addr)
 { return NULL; }
 static inline int rbt_memtype_copy_nth_element(struct memtype *out, loff_t pos)

arch/x86/mm/pat_rbtree.c

···
 	return err;
 }
 
-int rbt_memtype_erase(u64 start, u64 end)
+struct memtype *rbt_memtype_erase(u64 start, u64 end)
 {
 	struct memtype *data;
 
 	data = memtype_rb_exact_match(&memtype_rbroot, start, end);
 	if (!data)
-		return -EINVAL;
+		goto out;
 
 	rb_erase(&data->rb, &memtype_rbroot);
-	return 0;
+out:
+	return data;
 }
 
 struct memtype *rbt_memtype_lookup(u64 addr)