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Message-Id: <20140626204403.d4fadfadbfbba95a319b41f4@skynet.be> Date: Thu, 26 Jun 2014 20:44:03 +0200 From: Fabian Frederick <fabf@...net.be> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Bob Copeland <me@...copeland.com>, Andrew Morton <akpm@...ux-foundation.org> Subject: Re: [PATCH 1/1] FS/OMFS: block number sanity check during fill_super operation On Thu, 26 Jun 2014 11:35:57 -0700 Linus Torvalds <torvalds@...ux-foundation.org> wrote: > On Jun 26, 2014 11:28 AM, "Fabian Frederick" <fabf@...net.be> wrote: > > > > Sorry but I don't see a problem with 2^31 value. > > It's not really 2^31. > > It's *negative* 2^31. > > 1 is "int", so it's a signed number. With the shift it ends up being a > signed number with the high bit set. That's just a bad bad idea. > > Now, it just so happens that if you always compare it with unsigned > numbers, C promotion rules will end up promoting it to unsigned and it > happens to *work*, but that is more luck than design. > > So I'd suggest using 0x80000000 (which is unsigned) or use (1ul<<31) or > similar explicit C typing. Ok, I understand now. Thanks a lot for taking the time to explain Linus. It really means a lot to me. Fabian > > Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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