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 offset greater than 4GB on 32 bit kernels.

Fix the check by using sizeof(loff_t) to get size. In addition, make sure pgoff + length can be represented by a signed long huge page offset. This check is only necessary on 32 bit kernels.

Fixes: 63489f8e8211 ("hugetlbfs: check for pgoff value overflow") Cc: stable@vger.kernel.org Reported-by: Dan Rue dan.rue@linaro.org Signed-off-by: Mike Kravetz mike.kravetz@oracle.com --- fs/hugetlbfs/inode.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index b9a254dcc0e7..8450a1d75dfa 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -116,7 +116,8 @@ static void huge_pagevec_release(struct pagevec *pvec) * bit into account. */ #define PGOFF_LOFFT_MAX \ - (((1UL << (PAGE_SHIFT + 1)) - 1) << (BITS_PER_LONG - (PAGE_SHIFT + 1))) + (((1UL << (PAGE_SHIFT + 1)) - 1) << \ + ((sizeof(loff_t) * BITS_PER_BYTE) - (PAGE_SHIFT + 1)))

static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) { @@ -138,21 +139,32 @@ 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. */ - if (vma->vm_pgoff & PGOFF_LOFFT_MAX) + if ((loff_t)vma->vm_pgoff & (loff_t)PGOFF_LOFFT_MAX) return -EINVAL;

- /* must be huge page aligned */ + /* vm_pgoff must be huge page aligned */ if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT)) return -EINVAL;

+ /* + * Compute file offset of the end of this mapping + */ vma_len = (loff_t)(vma->vm_end - vma->vm_start); len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); - /* check for overflow */ + + /* Check to ensure this did not overflow loff_t */ if (len < vma_len) return -EINVAL;

+ /* + * On 32 bit systems, this check is necessary to ensure the last page + * of mapping can be represented as a signed long huge page index. + */ + if ((len >> huge_page_shift(h)) > LONG_MAX) + return -EINVAL; + inode_lock(inode); file_accessed(file);