mm: fix VMA heap bounds checking

After converting selinux to VMA heap check helper, the gcl triggers an
execheap SELinux denial, which is caused by a changed logic check.

Previously selinux only checked that the VMA range was within the VMA heap
range, and the implementation checks the intersection between the two
ranges, but the corner case (vm_end=start_brk, brk=vm_start) isn't handled
correctly.

Since commit 11250fd ("mm: factor out VMA stack and heap checks") was
only a function extraction, it seems that the issue was introduced by
commit 0db0c01 ("procfs: fix /proc/<pid>/maps heap check").  Let's
fix above corner cases, meanwhile, correct the wrong indentation of the
stack and heap check helpers.

Fixes: 11250fd ("mm: factor out VMA stack and heap checks")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Closes: https://lore.kernel.org/selinux/CAFqZXNv0SVT0fkOK6neP9AXbj3nxJ61JAY4+zJzvxqJaeuhbFw@mail.gmail.com/
Tested-by: Ondrej Mosnacek <omosnace@redhat.com>
Link: https://lkml.kernel.org/r/20231207152525.2607420-1-wangkefeng.wang@huawei.com
Cc: David Hildenbrand <david@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm.h

@@ -886,8 +886,8 @@ static inline bool vma_is_anonymous(struct vm_area_struct *vma)
  */
 static inline bool vma_is_initial_heap(const struct vm_area_struct *vma)
 {
-       return vma->vm_start <= vma->vm_mm->brk &&
-		vma->vm_end >= vma->vm_mm->start_brk;
+	return vma->vm_start < vma->vm_mm->brk &&
+		vma->vm_end > vma->vm_mm->start_brk;
 }
 
 /*
@@ -901,8 +901,8 @@ static inline bool vma_is_initial_stack(const struct vm_area_struct *vma)
 	 * its "stack".  It's not even well-defined for programs written
 	 * languages like Go.
 	 */
-       return vma->vm_start <= vma->vm_mm->start_stack &&
-	       vma->vm_end >= vma->vm_mm->start_stack;
+	return vma->vm_start <= vma->vm_mm->start_stack &&
+		vma->vm_end >= vma->vm_mm->start_stack;
 }
 
 static inline bool vma_is_temporary_stack(struct vm_area_struct *vma)