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From: Eric Biggers <ebiggers3@gmail.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	George Spelvin <linux@horizon.com>,
	Scott Bauer <sbauer@eng.utah.edu>,
	Andi Kleen <ak@linux.intel.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Greg KH <gregkh@linuxfoundation.org>,
	Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>,
	"Daniel J . Bernstein" <djb@cr.yp.to>
Subject: Re: [PATCH v3] siphash: add cryptographically secure hashtable function
Date: Tue, 13 Dec 2016 00:39:48 -0800	[thread overview]
Message-ID: <20161213083948.GA8994@zzz> (raw)
In-Reply-To: <20161212221832.10653-1-Jason@zx2c4.com>

On Mon, Dec 12, 2016 at 11:18:32PM +0100, Jason A. Donenfeld wrote:
> +	for (; data != end; data += sizeof(u64)) {
> +		m = get_unaligned_le64(data);
> +		v3 ^= m;
> +		SIPROUND;
> +		SIPROUND;
> +		v0 ^= m;
> +	}
> +#if defined(CONFIG_DCACHE_WORD_ACCESS) && BITS_PER_LONG == 64
> +	b |= le64_to_cpu(load_unaligned_zeropad(data) & bytemask_from_count(left));
> +#else

Hmm, I don't think you can really do load_unaligned_zeropad() without first
checking for 'left != 0'.  The fixup section for load_unaligned_zeropad()
assumes that rounding the pointer down to a word boundary will produce an
address from which an 'unsigned long' can be loaded.  But if 'left = 0' and we
happen to be on a page boundary with the next page unmapped, then this will not
be true and the second load will still fault.

Eric

  parent reply	other threads:[~2016-12-13  8:40 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-09 18:36 [PATCH] siphash: add cryptographically secure hashtable function Jason A. Donenfeld
2016-12-10 12:37 ` [kernel-hardening] " Greg KH
2016-12-11 15:30   ` Jason A. Donenfeld
2016-12-11 20:43     ` [kernel-hardening] " Greg KH
2016-12-12  3:48       ` [PATCH v2] " Jason A. Donenfeld
2016-12-12  4:01         ` Linus Torvalds
2016-12-12  5:48           ` Jason A. Donenfeld
2016-12-12 21:37             ` Linus Torvalds
2016-12-12 22:18               ` [PATCH v3] " Jason A. Donenfeld
2016-12-12 23:01                 ` Andi Kleen
2016-12-13  8:39                 ` Eric Biggers [this message]
2016-12-13 19:26                   ` Linus Torvalds
2016-12-13 22:43                   ` Jason A. Donenfeld
2016-12-13 22:48                   ` [PATCH v4] " Jason A. Donenfeld
2016-12-12  5:42         ` [PATCH v2] " Eric Biggers
2016-12-12 21:17           ` Jason A. Donenfeld
2016-12-10 14:17 ` [PATCH] " Vegard Nossum
2016-12-10 15:35   ` George Spelvin
2016-12-10 18:13   ` Jean-Philippe Aumasson
  -- strict thread matches above, loose matches on Subject: below --
2016-12-12 23:04 [PATCH v3] " Jason A. Donenfeld
2016-12-13 19:25 ` Linus Torvalds
2016-12-13 23:36   ` Jason A. Donenfeld

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