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Message-ID: <CADYN=9+FzfFt8kKjw-hnHx7CdPbTsH0OsNs1TAGHa6Hi7ndbZQ@mail.gmail.com> Date: Mon, 2 Apr 2018 18:21:01 +0200 From: Anders Roxell <anders.roxell@...aro.org> To: Mike Kravetz <mike.kravetz@...cle.com> Cc: linux-mm@...ck.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Michal Hocko <mhocko@...nel.org>, Yisheng Xie <xieyisheng1@...wei.com>, "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Nic Losby <blurbdust@...il.com>, Dan Rue <dan.rue@...aro.org>, Andrew Morton <akpm@...ux-foundation.org>, stable@...r.kernel.org Subject: Re: [PATCH v2] hugetlbfs: fix bug in pgoff overflow checking On 30 March 2018 at 16:54, Mike Kravetz <mike.kravetz@...cle.com> wrote: > 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). > > Fixes: 63489f8e8211 ("hugetlbfs: check for pgoff value overflow") > Cc: <stable@...r.kernel.org> > Reported-by: Dan Rue <dan.rue@...aro.org> > Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com> Tested-by: Anders Roxell <anders.roxell@...aro.org> > --- > 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)) > -- > 2.13.6 >
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