From 5df63c2a149ae65a9ec239e7c2af44efa6f79beb Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Thu, 5 Apr 2018 16:18:21 -0700 Subject: [PATCH] hugetlbfs: fix bug in pgoff overflow checking This is a fix for a regression in 32 bit kernels caused by an invalid check for pgoff overflow in hugetlbfs mmap setup. The check incorrectly specified that the size of a loff_t was the same as the size of a long. The regression prevents mapping hugetlbfs files at offsets greater than 4GB on 32 bit kernels. On 32 bit kernels conversion from a page based unsigned long can not overflow a loff_t byte offset. Therefore, skip this check if sizeof(unsigned long) != sizeof(loff_t). Link: http://lkml.kernel.org/r/20180330145402.5053-1-mike.kravetz@oracle.com Fixes: 63489f8e8211 ("hugetlbfs: check for pgoff value overflow") Reported-by: Dan Rue Signed-off-by: Mike Kravetz Tested-by: Anders Roxell Cc: Michal Hocko Cc: Yisheng Xie Cc: "Kirill A . Shutemov" Cc: Nic Losby Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/hugetlbfs/inode.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index b9a254dcc0e7..d508c7844681 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -138,10 +138,14 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) /* * page based offset in vm_pgoff could be sufficiently large to - * overflow a (l)off_t when converted to byte offset. + * overflow a loff_t when converted to byte offset. This can + * only happen on architectures where sizeof(loff_t) == + * sizeof(unsigned long). So, only check in those instances. */ - if (vma->vm_pgoff & PGOFF_LOFFT_MAX) - return -EINVAL; + if (sizeof(unsigned long) == sizeof(loff_t)) { + if (vma->vm_pgoff & PGOFF_LOFFT_MAX) + return -EINVAL; + } /* must be huge page aligned */ if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))