From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754610AbbLYHkZ (ORCPT ); Fri, 25 Dec 2015 02:40:25 -0500 Received: from helcar.hengli.com.au ([209.40.204.226]:35463 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753180AbbLYHkT (ORCPT ); Fri, 25 Dec 2015 02:40:19 -0500 Date: Fri, 25 Dec 2015 15:40:05 +0800 From: Herbert Xu To: Dmitry Vyukov Cc: syzkaller@googlegroups.com, davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, kcc@google.com, glider@google.com, edumazet@google.com, sasha.levin@oracle.com, keescook@google.com Subject: [PATCH v2] crypto: algif_skcipher - Require setkey before accept(2) Message-ID: <20151225074005.GA14690@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Core X-Newsgroups: apana.lists.os.linux.cryptoapi,apana.lists.os.linux.kernel User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dmitry Vyukov wrote: > > I am testing with your two patches: > crypto: algif_skcipher - Use new skcipher interface > crypto: algif_skcipher - Require setkey before accept(2) > on top of a88164345b81292b55a8d4829fdd35c8d611cd7d (Dec 23). You sent the email to everyone on the original CC list except me. Please don't do that. > Now the following program causes a bunch of use-after-frees and them > kills kernel: Yes there is an obvious bug in the patch that Julia Lawall has responded to in another thread. Here is a fixed version. ---8<-- Some cipher implementations will crash if you try to use them without calling setkey first. This patch adds a check so that the accept(2) call will fail with -ENOKEY if setkey hasn't been done on the socket yet. Cc: stable@vger.kernel.org Reported-by: Dmitry Vyukov Signed-off-by: Herbert Xu diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 5c756b3..f4431bc 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -31,6 +31,11 @@ struct skcipher_sg_list { struct scatterlist sg[0]; }; +struct skcipher_tfm { + struct crypto_skcipher *skcipher; + bool has_key; +}; + struct skcipher_ctx { struct list_head tsgl; struct af_alg_sgl rsgl; @@ -750,17 +755,41 @@ static struct proto_ops algif_skcipher_ops = { static void *skcipher_bind(const char *name, u32 type, u32 mask) { - return crypto_alloc_skcipher(name, type, mask); + struct skcipher_tfm *tfm; + struct crypto_skcipher *skcipher; + + tfm = kzalloc(sizeof(*tfm), GFP_KERNEL); + if (!tfm) + return ERR_PTR(-ENOMEM); + + skcipher = crypto_alloc_skcipher(name, type, mask); + if (IS_ERR(skcipher)) { + kfree(tfm); + return ERR_CAST(skcipher); + } + + tfm->skcipher = skcipher; + + return tfm; } static void skcipher_release(void *private) { - crypto_free_skcipher(private); + struct skcipher_tfm *tfm = private; + + crypto_free_skcipher(tfm->skcipher); + kfree(tfm); } static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen) { - return crypto_skcipher_setkey(private, key, keylen); + struct skcipher_tfm *tfm = private; + int err; + + err = crypto_skcipher_setkey(tfm->skcipher, key, keylen); + tfm->has_key = !err; + + return err; } static void skcipher_wait(struct sock *sk) @@ -792,20 +821,25 @@ static int skcipher_accept_parent(void *private, struct sock *sk) { struct skcipher_ctx *ctx; struct alg_sock *ask = alg_sk(sk); - unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(private); + struct skcipher_tfm *tfm = private; + struct crypto_skcipher *skcipher = tfm->skcipher; + unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(skcipher); + + if (!tfm->has_key) + return -ENOKEY; ctx = sock_kmalloc(sk, len, GFP_KERNEL); if (!ctx) return -ENOMEM; - ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(private), + ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(skcipher), GFP_KERNEL); if (!ctx->iv) { sock_kfree_s(sk, ctx, len); return -ENOMEM; } - memset(ctx->iv, 0, crypto_skcipher_ivsize(private)); + memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher)); INIT_LIST_HEAD(&ctx->tsgl); ctx->len = len; @@ -818,7 +852,7 @@ static int skcipher_accept_parent(void *private, struct sock *sk) ask->private = ctx; - skcipher_request_set_tfm(&ctx->req, private); + skcipher_request_set_tfm(&ctx->req, skcipher); skcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_complete, &ctx->completion); -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt