Date: Wed, 17 Sep 2003 16:56:28 +0900 From: Hajimu UMEMOTO <ume@freebsd.org> To: zevlg@yandex.ru Cc: core@kame.net Subject: Re: possible rijndael bug Message-ID: <ygepthz7sr7.wl%ume@bisd.hitachi.co.jp> In-Reply-To: <3F680C78.000003.13537@tide.yandex.ru> References: <3F680C78.000003.13537@tide.yandex.ru>
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Hi,
>>>>> On Wed, 17 Sep 2003 11:25:44 +0400 (MSD)
>>>>> zevlg@yandex.ru ("lg") said:
zevlg> I recently examined rijndael implementation, which ships in sys/crypto/rijndael and there
zevlg> is code in function rijndael_padEncrypt()(from rijndael-api-fst.c):
zevlg> numBlocks = inputOctets/16;
zevlg> ...
zevlg> ...
zevlg> padLen = 16 - (inputOctets - 16*numBlocks);
zevlg> if (padLen > 0 && padLen <= 16)
zevlg> panic("...");
zevlg> bcopy(input, block, 16 - padLen);
zevlg> for (cp = block + 16 - padLen; cp < block + 16; cp++)
zevlg> *cp = padLen;
zevlg> rijndaelEncrypt(block, outBuffer, key->keySched, key->ROUNDS);
zevlg> ...
zevlg> so padLen check will always success and it surely will panic, or even if we admit that
zevlg> padLen check is bypassed(what is impossible i think) then bcopy() will be called with
zevlg> larger size argument then size of block array or with negative size. Isn't this padLen
zevlg> check is unneeded? or maybe it should look like 'if (padLen <= 0 || padLen > 16)'?
I saw it during working on next KAME merge into 5-CURRENT.
KAME/NetBSD uses assert() here like:
assert(padLen > 0 && padLen <= 16);
Since FreeBSD doesn't have assert() in kernel, this line was changed
to:
if (padLen > 0 && padLen <= 16)
return BAD_CIPHER_STATE;
for KAME/FreeBSD. Since if expression is true, the assert() macro
does nothing, the expression seems wrong, and it should be:
if (padLen <= 0 || padLen > 16)
return BAD_CIPHER_STATE;
as you pointed out.
Sincerely,
--
Hajimu UMEMOTO @ Internet Mutual Aid Society Yokohama, Japan
ume@mahoroba.org ume@bisd.hitachi.co.jp ume@{,jp.}FreeBSD.org
http://www.imasy.org/~ume/
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