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 kernel disables some optimizations by using the "-fno-strict-overflow" option, there is still a risk. 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> --- fs/hugetlbfs/inode.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 7b17ccfa039d..60f3010b0f71 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -155,9 +155,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) 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
