From: Linke Li <lilinke99@xxxxxxxxx> ``` vma_len = (loff_t)(vma->vm_end - vma->vm_start); len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); /* check for overflow */ if (len < vma_len) return -EINVAL; ``` There is a signed integer overflow in the code, which is undefined behavior according to the C stacnard. Although this works, it's still a bit ugly and static checkers will complain. Using macro "check_add_overflow" to do the overflow check can effectively detect integer overflow and avoid any undefined behavior. Signed-off-by: Linke Li <lilinke99@xxxxxxxxx> --- v3: fix checkpatch warning and better description. fs/hugetlbfs/inode.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 7b17ccfa039d..326a8c0af5f6 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -154,10 +154,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT)) return -EINVAL; - vma_len = (loff_t)(vma->vm_end - vma->vm_start); - len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); - /* check for overflow */ - if (len < vma_len) + if (check_add_overflow(vma_len, (loff_t)vma->vm_pgoff << PAGE_SHIFT, &len)) return -EINVAL; inode_lock(inode); -- 2.25.1
