[PATCH] xdr_array and calloc security fix

[Wolfram Gloger]

> > But (a > a * b || b > a * b) should work, shouldn't it?
> 
> No. For a=1 b=2 this will give the correct answer (no overflow), but
> for a=0x6000000 b=64 it will give incorrect one (no overflow, while
> 0x180000000LL certainly doesn't fit into 32-bits (but 0x80000000 is
> still bigger than any of the operands).

Ok, if we're going to have two comparisions anyway, I'd suggest we
assume at least 32bits and use

a >= 46340 || b >= 46340

(46340 <= sqrt(2^31), if I did my math correctly)
Of course this will detect some cases as overflow which actually
aren't, but that is harmless.

Regards,
Wolfram.