[PATCH][next] afs: fix integer overflow when shifting 1 more than 32 places

David Howells dhowells at redhat.com
Wed Apr 11 07:10:16 PDT 2018


Colin Ian King <colin.king at canonical.com> wrote:

> >> -	mask = (1 << nr_slots) - 1;
> >> +	mask = (1ULL << nr_slots) - 1;
> > 
> > nr_slots cannot be larger than 9, so what I wrote is actually fine and is
> > more efficient on a 32-bit machine.
> 
> ok, sorry about the noise.

It would be possible to cast the value to u64 before assigning it, I suppose.
Would that help?  E.g.:

	mask = (u64)((1 << nr_slots) - 1);

It looks a bit odd, though, since the cast is made implicitly anyway.

David



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