linux-kernel - Re: Linux 3.6-rc5

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Date:	Sun, 9 Sep 2012 14:00:00 -0700
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Mathias Krause <minipli@...glemail.com>
Cc:	Romain Francoise <romain@...bokech.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: Linux 3.6-rc5

On Sun, Sep 09, 2012 at 10:09:10PM +0200, Mathias Krause wrote:
>
> It happens with the C variants of SHA1 and AES, too. You can easily
> trigger the bug with Steffen's crconf[1]:
> 
> $ crconf add alg "authenc(hmac(sha1-generic),cbc(aes-generic))" type 3
> 
> So the problem is likely not related to sha1-ssse3.ko or aesni-intel.ko.

Thanks! I think this patch should fix the problem.  Can someone
please confirm this?

crypto: authenc - Fix crash with zero-length assoc data

The authenc code doesn't deal with zero-length associated data
correctly and ends up constructing a zero-length sg entry which
causes a crash when it's fed into the crypto system.

This patch fixes this by avoiding the code-path that triggers
the SG construction if we have no associated data.

This isn't the most optimal fix as it means that we'll end up
using the fallback code-path even when we could still execute
the digest function.  However, this isn't a big deal as nobody
but the test path would supply zero-length associated data.

Reported-by: Romain Francoise <romain@...bokech.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/crypto/authenc.c b/crypto/authenc.c
index 5ef7ba6..d0583a4 100644
--- a/crypto/authenc.c
+++ b/crypto/authenc.c
@@ -336,7 +336,7 @@ static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
 		cryptlen += ivsize;
 	}
 
-	if (sg_is_last(assoc)) {
+	if (req->assoclen && sg_is_last(assoc)) {
 		authenc_ahash_fn = crypto_authenc_ahash;
 		sg_init_table(asg, 2);
 		sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);
@@ -490,7 +490,7 @@ static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
 		cryptlen += ivsize;
 	}
 
-	if (sg_is_last(assoc)) {
+	if (req->assoclen && sg_is_last(assoc)) {
 		authenc_ahash_fn = crypto_authenc_ahash;
 		sg_init_table(asg, 2);
 		sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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