On 07/20/23 22:49, Linke Li wrote: > 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); I don't think you wanted to delete the above line as ... > - 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)) .. vma_len is uninitialized here. > return -EINVAL; > > inode_lock(inode); > -- > 2.25.1 > -- Mike Kravetz
