Re: error in msync(2) or am I missing something?
Bill Hawes (whawes@star.net)
Fri, 04 Sep 1998 11:24:41 -0400
Tigran Aivazian wrote:
> In the msync(2) (source mm/filemap.c/sys_msync()) function there is a piece of
> code:
>
> len = (len + ~PAGE_MASK) & PAGE_MASK;
> end = start + len;
> if (end < start)
> goto out;
> if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
> goto out;
> error = 0;
> if (end == start)
> goto out;
>
> Now, len is size_t (unsigned int) so it can hardly ever become negative. So,
> can't one simply rewrite the code as:
>
> if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
> goto out;
> error = 0;
> if (!len)
> goto out;
The test for end < start is meant to catch wrap-around.
Regards,
Bill
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