Re: [PATCH 1/1] xfs: check for possible overflow in xfs_ioc_trim

Tomas Racek
2012-07-31T10:32:39Z

> > +
> > + if (range.start > ULLONG_MAX - BBSIZE)
> > + return -XFS_ERROR(EINVAL);
> > +
>
> There's no point checking for overflow on the range start - what we
> need to check is whether it is larger than the size of the
> filesystem. We do that after the conversion of range.start to basic
> blocks, so that check needs to be promoted to before this. i.e.
>
> if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks))
> return -XFS_ERROR(EINVAL);
>
> > start = BTOBB(range.start);
> > end = start + BTOBBT(range.len) - 1;
> > minlen = BTOBB(max_t(u64, granularity, range.minlen));
>
> And that will prevent the overflow in BTOBB() just as effectively...

You're right, that's a far better way, I'll change it so.

Thanks!

Tomas