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    SubjectRe: [PATCH 6/6] vfs: introduce FMODE_NEG_OFFSET for allowing negative f_pos
    Date
    Wu Fengguang <fengguang.wu@intel.com> writes:

    > +static int
    > +__negative_fpos_check(struct file *file, loff_t pos, size_t count)
    > +{
    > + /*
    > + * pos or pos+count is negative here, check overflow.
    > + * too big "count" will be caught in rw_verify_area().
    > + */
    > + if ((pos < 0) && (pos + count < pos))
    > + return -EOVERFLOW;
    > + if (file->f_mode & FMODE_NEG_OFFSET)
    > + return 0;
    > + return -EINVAL;
    > +}
    > +
    > /*
    > * rw_verify_area doesn't like huge counts. We limit
    > * them to something that fits in "int" so that others
    > @@ -222,8 +236,11 @@ int rw_verify_area(int read_write, struc
    > if (unlikely((ssize_t) count < 0))
    > return retval;
    > pos = *ppos;
    > - if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
    > - return retval;
    > + if (unlikely((pos < 0) || (loff_t) (pos + count) < 0)) {
    > + retval = __negative_fpos_check(file, pos, count);
    > + if (retval)
    > + return retval;
    > + }
    >
    > if (unlikely(inode->i_flock && mandatory_lock(inode))) {
    > retval = locks_mandatory_area(

    Um... How do lseek() work? It sounds like to violate error code range.
    --
    OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>


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