[PATCH] x86_64 memleak from malicious 32bit elf program

malicious 32bit app can have an elf section at 0xffffe000.  During
exec of this app, we will have a memory leak as insert_vm_struct() is
not checking for return value in syscall32_setup_pages() and thus not
freeing the vma allocated for the vsyscall page.

Check the return value and free the vma incase of failure.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86_64/ia32/syscall32.c

@@ -57,6 +57,7 @@ int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
 	int npages = (VSYSCALL32_END - VSYSCALL32_BASE) >> PAGE_SHIFT;
 	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
+	int ret;
 
 	vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 	if (!vma)
@@ -78,7 +79,11 @@ int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
 	vma->vm_mm = mm;
 
 	down_write(&mm->mmap_sem);
-	insert_vm_struct(mm, vma);
+	if ((ret = insert_vm_struct(mm, vma))) {
+		up_write(&mm->mmap_sem);
+		kmem_cache_free(vm_area_cachep, vma);
+		return ret;
+	}
 	mm->total_vm += npages;
 	up_write(&mm->mmap_sem);
 	return 0;