From patchwork Tue Jan 14 17:33:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Vasut X-Patchwork-Id: 3487211 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E983D9F2E9 for ; Tue, 14 Jan 2014 17:35:40 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B175820221 for ; Tue, 14 Jan 2014 17:35:39 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BDC3820225 for ; Tue, 14 Jan 2014 17:35:34 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W37t6-0001p6-A9; Tue, 14 Jan 2014 17:34:52 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W37sx-00037R-K1; Tue, 14 Jan 2014 17:34:43 +0000 Received: from mail-out.m-online.net ([212.18.0.10]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W37sf-00035F-G6 for linux-arm-kernel@lists.infradead.org; Tue, 14 Jan 2014 17:34:29 +0000 Received: from frontend1.mail.m-online.net (frontend1.mail.intern.m-online.net [192.168.8.180]) by mail-out.m-online.net (Postfix) with ESMTP id 3f3f0h49qzz3hjNX; Tue, 14 Jan 2014 18:33:56 +0100 (CET) X-Auth-Info: yYce5QmRI3Kzjd/PllHa/0kVEmNJMlWR+OkqicwlX/w= Received: from chi.lan (unknown [195.140.253.167]) by smtp-auth.mnet-online.de (Postfix) with ESMTPA id 3f3f0g6zq1zbbhH; Tue, 14 Jan 2014 18:33:55 +0100 (CET) From: Marek Vasut To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/3] crypto: Fix the pointer voodoo in unaligned ahash Date: Tue, 14 Jan 2014 18:33:47 +0100 Message-Id: <1389720829-5963-2-git-send-email-marex@denx.de> X-Mailer: git-send-email 1.8.4.2 In-Reply-To: <1389720829-5963-1-git-send-email-marex@denx.de> References: <1389720829-5963-1-git-send-email-marex@denx.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140114_123425_860303_6A8C591A X-CRM114-Status: GOOD ( 18.11 ) X-Spam-Score: -1.9 (-) Cc: Marek Vasut , Fabio Estevam , Herbert Xu , Tom Lendacky , linux-crypto@vger.kernel.org, Shawn Guo , "David S. Miller" X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add documentation for the pointer voodoo that is happening in crypto/ahash.c in ahash_op_unaligned(). This code is quite confusing, so add a beefy chunk of documentation. Moreover, make sure the mangled request is completely restored after finishing this unaligned operation. This means restoring all of .result, .priv, .base.data and .base.complete . Also, remove the crypto_completion_t complete = ... line present in the ahash_op_unaligned_done() function. This type actually declares a function pointer, which is very confusing. Finally, yet very important nonetheless, make sure the req->priv is free()'d only after the original request is restored in ahash_op_unaligned_done(). The req->priv data must not be free()'d before that in ahash_op_unaligned_finish(), since we would be accessing previously free()'d data in ahash_op_unaligned_done() and cause corruption. Signed-off-by: Marek Vasut Cc: David S. Miller Cc: Fabio Estevam Cc: Herbert Xu Cc: Shawn Guo Cc: Tom Lendacky --- crypto/ahash.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 54 insertions(+), 11 deletions(-) diff --git a/crypto/ahash.c b/crypto/ahash.c index a92dc38..5ca8ede 100644 --- a/crypto/ahash.c +++ b/crypto/ahash.c @@ -29,6 +29,7 @@ struct ahash_request_priv { crypto_completion_t complete; void *data; + void *priv; u8 *result; void *ubuf[] CRYPTO_MINALIGN_ATTR; }; @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct ahash_request *req, int err) if (!err) memcpy(priv->result, req->result, crypto_ahash_digestsize(crypto_ahash_reqtfm(req))); - - kzfree(priv); } -static void ahash_op_unaligned_done(struct crypto_async_request *req, int err) +static void ahash_op_unaligned_done(struct crypto_async_request *areq, int err) { - struct ahash_request *areq = req->data; - struct ahash_request_priv *priv = areq->priv; - crypto_completion_t complete = priv->complete; - void *data = priv->data; + struct ahash_request *req = areq->data; + struct ahash_request_priv *priv = req->priv; + struct crypto_async_request *data; + + /* + * Restore the original request, see ahash_op_unaligned() for what + * goes where. + * + * The "struct ahash_request *req" here is in fact the "req.base" + * from the ADJUSTED request from ahash_op_unaligned(), thus as it + * is a pointer to self, it is also the ADJUSTED "req" . + */ + + /* First copy req->result into req->priv.result */ + ahash_op_unaligned_finish(req, err); - ahash_op_unaligned_finish(areq, err); + /* Restore the original crypto request. */ + req->result = priv->result; + req->base.complete = priv->complete; + req->base.data = priv->data; + req->priv = priv->priv; - areq->base.complete = complete; - areq->base.data = data; + /* Free the req->priv.priv from the ADJUSTED request. */ + kzfree(priv); - complete(&areq->base, err); + /* Complete the ORIGINAL request. */ + data = req->base.data; + req->base.complete(data, err); } static int ahash_op_unaligned(struct ahash_request *req, @@ -234,9 +250,36 @@ static int ahash_op_unaligned(struct ahash_request *req, if (!priv) return -ENOMEM; + /* + * WARNING: Voodoo programming below! + * + * The code below is obscure and hard to understand, thus explanation + * is necessary. See include/crypto/hash.h and include/linux/crypto.h + * to understand the layout of structures used here! + * + * The code here will replace portions of the ORIGINAL request with + * pointers to new code and buffers so the hashing operation can store + * the result in aligned buffer. We will call the modified request + * an ADJUSTED request. + * + * The newly mangled request will look as such: + * + * req { + * .result = ADJUSTED[new aligned buffer] + * .base.complete = ADJUSTED[pointer to completion function] + * .base.data = ADJUSTED[*req (pointer to self)] + * .priv = ADJUSTED[new priv] { + * .result = ORIGINAL(result) + * .complete = ORIGINAL(base.complete) + * .data = ORIGINAL(base.data) + * .priv = ORIGINAL(priv) + * } + */ + priv->result = req->result; priv->complete = req->base.complete; priv->data = req->base.data; + priv->priv = req->priv; req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1); req->base.complete = ahash_op_unaligned_done;