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    Subject[PATCH 4.14 48/49] hugetlbfs: fix bug in pgoff overflow checking
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Mike Kravetz <mike.kravetz@oracle.com>

    commit 5df63c2a149ae65a9ec239e7c2af44efa6f79beb upstream.

    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 <dan.rue@linaro.org>
    Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
    Tested-by: Anders Roxell <anders.roxell@linaro.org>
    Cc: Michal Hocko <mhocko@kernel.org>
    Cc: Yisheng Xie <xieyisheng1@huawei.com>
    Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
    Cc: Nic Losby <blurbdust@gmail.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/hugetlbfs/inode.c | 10 +++++++---
    1 file changed, 7 insertions(+), 3 deletions(-)

    --- a/fs/hugetlbfs/inode.c
    +++ b/fs/hugetlbfs/inode.c
    @@ -148,10 +148,14 @@ static int hugetlbfs_file_mmap(struct fi

    /*
    * 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))

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