From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBB23C04AB7 for ; Tue, 14 May 2019 23:14:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDF322166E for ; Tue, 14 May 2019 23:14:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557875690; bh=62wRBq+vd5/3w97GewxX5Jxc2LoBBdS+JqDvjbZG5RQ=; h=From:To:Cc:Subject:Date:List-ID:From; b=uidWpQFXpYMqfHZV6TN6hRo9kjFD19s1jAAl8J8kZ/qUlSZtvfamwC1mgZUJ2cUPH R1Ie4oxmxrGIFRiP/M31qqqjOmk1X+quuZoe2xKxjA/FPOw+lP++MBGQXAwT3Y6+lm x4yxrPDswHrZn3l0+vy2mXbthwVUCG65Kg6KI/4k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726648AbfENXOt (ORCPT ); Tue, 14 May 2019 19:14:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:38098 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726622AbfENXOt (ORCPT ); Tue, 14 May 2019 19:14:49 -0400 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9468420873; Tue, 14 May 2019 23:14:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557875688; bh=62wRBq+vd5/3w97GewxX5Jxc2LoBBdS+JqDvjbZG5RQ=; h=From:To:Cc:Subject:Date:From; b=byZseif7A6jI4T+UQ/x6vute/lg0qIVNK4Bt5OH7qEXCduhxKfGkfnPskAYTmxeg1 l0jUNlybRTmFoeeD4XggfBHvC+foTdSD8ocMr6hhr0o2STCRfCd4H07LWZ35ydWPoQ cP1dR2GFfWJf4UY2cUHHyysPkxknJSFumQRCWrVM= From: Eric Biggers To: linux-crypto@vger.kernel.org, Herbert Xu Cc: Corentin Labbe , stable@vger.kernel.org, Kees Cook Subject: [PATCH] crypto: hash - fix incorrect HASH_MAX_DESCSIZE Date: Tue, 14 May 2019 16:13:15 -0700 Message-Id: <20190514231315.7729-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.1020.gf2820cf01a-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org From: Eric Biggers The "hmac(sha3-224-generic)" algorithm has a descsize of 368 bytes, which is greater than HASH_MAX_DESCSIZE (360) which is only enough for sha3-224-generic. The check in shash_prepare_alg() doesn't catch this because the HMAC template doesn't set descsize on the algorithms, but rather sets it on each individual HMAC transform. This causes a stack buffer overflow when SHASH_DESC_ON_STACK() is used with hmac(sha3-224-generic). Fix it by increasing HASH_MAX_DESCSIZE to the real maximum. Also add a sanity check to hmac_init(). This was detected by the improved crypto self-tests in v5.2, by loading the tcrypt module with CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y enabled. I didn't notice this bug when I ran the self-tests by requesting the algorithms via AF_ALG (i.e., not using tcrypt), probably because the stack layout differs in the two cases and that made a difference here. KASAN report: BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:359 [inline] BUG: KASAN: stack-out-of-bounds in shash_default_import+0x52/0x80 crypto/shash.c:223 Write of size 360 at addr ffff8880651defc8 by task insmod/3689 CPU: 2 PID: 3689 Comm: insmod Tainted: G E 5.1.0-10741-g35c99ffa20edd #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x86/0xc5 lib/dump_stack.c:113 print_address_description+0x7f/0x260 mm/kasan/report.c:188 __kasan_report+0x144/0x187 mm/kasan/report.c:317 kasan_report+0x12/0x20 mm/kasan/common.c:614 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x137/0x190 mm/kasan/generic.c:191 memcpy+0x37/0x50 mm/kasan/common.c:125 memcpy include/linux/string.h:359 [inline] shash_default_import+0x52/0x80 crypto/shash.c:223 crypto_shash_import include/crypto/hash.h:880 [inline] hmac_import+0x184/0x240 crypto/hmac.c:102 hmac_init+0x96/0xc0 crypto/hmac.c:107 crypto_shash_init include/crypto/hash.h:902 [inline] shash_digest_unaligned+0x9f/0xf0 crypto/shash.c:194 crypto_shash_digest+0xe9/0x1b0 crypto/shash.c:211 generate_random_hash_testvec.constprop.11+0x1ec/0x5b0 crypto/testmgr.c:1331 test_hash_vs_generic_impl+0x3f7/0x5c0 crypto/testmgr.c:1420 __alg_test_hash+0x26d/0x340 crypto/testmgr.c:1502 alg_test_hash+0x22e/0x330 crypto/testmgr.c:1552 alg_test.part.7+0x132/0x610 crypto/testmgr.c:4931 alg_test+0x1f/0x40 crypto/testmgr.c:4952 Fixes: b68a7ec1e9a3 ("crypto: hash - Remove VLA usage") Reported-by: Corentin Labbe Cc: # v4.20+ Cc: Kees Cook Signed-off-by: Eric Biggers --- crypto/hmac.c | 2 ++ include/crypto/hash.h | 8 +++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/crypto/hmac.c b/crypto/hmac.c index a68c1266121f5..241b1868c1d01 100644 --- a/crypto/hmac.c +++ b/crypto/hmac.c @@ -157,6 +157,8 @@ static int hmac_init_tfm(struct crypto_tfm *tfm) parent->descsize = sizeof(struct shash_desc) + crypto_shash_descsize(hash); + if (WARN_ON(parent->descsize > HASH_MAX_DESCSIZE)) + return -EINVAL; ctx->hash = hash; return 0; diff --git a/include/crypto/hash.h b/include/crypto/hash.h index d21bea2c43829..d6702b4a457f9 100644 --- a/include/crypto/hash.h +++ b/include/crypto/hash.h @@ -150,7 +150,13 @@ struct shash_desc { }; #define HASH_MAX_DIGESTSIZE 64 -#define HASH_MAX_DESCSIZE 360 + +/* + * Worst case is hmac(sha3-224-generic). Its context is a nested 'shash_desc' + * containing a 'struct sha3_state'. + */ +#define HASH_MAX_DESCSIZE (sizeof(struct shash_desc) + 360) + #define HASH_MAX_STATESIZE 512 #define SHASH_DESC_ON_STACK(shash, ctx) \ -- 2.21.0.1020.gf2820cf01a-goog