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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 64632C433E0 for ; Fri, 5 Feb 2021 17:41:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 155CB64DC4 for ; Fri, 5 Feb 2021 17:41:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231481AbhBEP6S (ORCPT ); Fri, 5 Feb 2021 10:58:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230374AbhBEPx1 (ORCPT ); Fri, 5 Feb 2021 10:53:27 -0500 Received: from mail-wm1-x349.google.com (mail-wm1-x349.google.com [IPv6:2a00:1450:4864:20::349]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DC0AC06178C for ; Fri, 5 Feb 2021 09:35:09 -0800 (PST) Received: by mail-wm1-x349.google.com with SMTP id q24so4071746wmc.1 for ; Fri, 05 Feb 2021 09:35:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=6RV3PXvNWDRRLwJfhc9nA9uOtjOO4vRR2YJTlHhgy1g=; b=hr9DzLw8PMFXDmOtc8ZAyVLRhSu9H1GXAWRc7Isd9/XTI8Cgi/jOQVN1GFDvZnERyB G0HDSX6x8jQqkjNbE1UygZ3nJdUqxCSAPKSLVU27KQJjuRq2fa0ClujER0+PhSTzUcbZ nrhIBgxy8C9/vLXSIHaHysZ86Cf8ZxwaoECfAGez4vWWEVDoSH037sAnwgHeL68Yg5iV FjqojbgDKu9rTiWhHFSCGcCAnibfMdcmw/QUZF+vozj8e9iaXiBtzMtFGaPsuvLT80Kw 2VNm/yfw0oadQd2OIkqOcJCfOagcSL+70vJBOSCrH8Uczn7HUXpEpK1ijgH8yi9KwdHb prUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=6RV3PXvNWDRRLwJfhc9nA9uOtjOO4vRR2YJTlHhgy1g=; b=RIzzxsiIzFJ5/XguNrbRNhx7nj/VdC6hr307MCj3iGgweEK5qnuqE1yycnMod72v5p anDw+nTBV9ciTQTjmPaRc2aliRpTLyxbm88VMGpQroeORqoepvwHNpbmQqpEyMcCYG3X U/+68cSRbl5HRZqFJzdO9RpKQGdHkR4bIrxl23Ojw7IPgZpg0AGjKu9BQlLWnCWsGhPR j/uDf7DVKNfPJZD9FQAXVTr48162J8H3laow0WBiwvGLq63ZOt10dWp/SL3OXikx8zPA o6WYKOmGvVsYsDBmmXTBnuqFzJTP4TXaGgy8OG7IVgNmxsaL7F4Jiuw7Zo9gKfBnu+w3 LmUQ== X-Gm-Message-State: AOAM531MbRC9Uu0g56RBego8mNuvqJ1iuRXAl8j6Twf2mIWu91CeKb0G rXDpnFE91c81b+yZq/1ad5jbvNEgYGX5SHB5 X-Google-Smtp-Source: ABdhPJytRzXE5voKMAWTVE7tb2OGC2+Y1oliS+AIv9OdSPsqoc+dVJE3s1RRE+LkSF8dIUprMqGcmE4wi/aHTTwX Sender: "andreyknvl via sendgmr" X-Received: from andreyknvl3.muc.corp.google.com ([2a00:79e0:15:13:edb8:b79c:2e20:e531]) (user=andreyknvl job=sendgmr) by 2002:a1c:3185:: with SMTP id x127mr4375625wmx.117.1612546507585; Fri, 05 Feb 2021 09:35:07 -0800 (PST) Date: Fri, 5 Feb 2021 18:34:41 +0100 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.30.0.365.g02bc693789-goog Subject: [PATCH v3 mm 07/13] kasan, mm: fail krealloc on freed objects From: Andrey Konovalov To: Andrew Morton , Catalin Marinas , Vincenzo Frascino , Dmitry Vyukov , Alexander Potapenko , Marco Elver Cc: Will Deacon , Andrey Ryabinin , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, if krealloc() is called on a freed object with KASAN enabled, it allocates and returns a new object, but doesn't copy any memory from the old one as ksize() returns 0. This makes the caller believe that krealloc() succeeded (KASAN report is printed though). This patch adds an accessibility check into __do_krealloc(). If the check fails, krealloc() returns NULL. This check duplicates the one in ksize(); this is fixed in the following patch. This patch also adds a KASAN-KUnit test to check krealloc() behaviour when it's called on a freed object. Reviewed-by: Marco Elver Signed-off-by: Andrey Konovalov --- lib/test_kasan.c | 20 ++++++++++++++++++++ mm/slab_common.c | 3 +++ 2 files changed, 23 insertions(+) diff --git a/lib/test_kasan.c b/lib/test_kasan.c index ffebad2f0e6e..1328c468fdb5 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -353,6 +353,25 @@ static void krealloc_pagealloc_less_oob(struct kunit *test) KMALLOC_MAX_CACHE_SIZE + 201); } +/* + * Check that krealloc() detects a use-after-free, returns NULL, + * and doesn't unpoison the freed object. + */ +static void krealloc_uaf(struct kunit *test) +{ + char *ptr1, *ptr2; + int size1 = 201; + int size2 = 235; + + ptr1 = kmalloc(size1, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1); + kfree(ptr1); + + KUNIT_EXPECT_KASAN_FAIL(test, ptr2 = krealloc(ptr1, size2, GFP_KERNEL)); + KUNIT_ASSERT_PTR_EQ(test, (void *)ptr2, NULL); + KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)ptr1); +} + static void kmalloc_oob_16(struct kunit *test) { struct { @@ -1050,6 +1069,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(krealloc_less_oob), KUNIT_CASE(krealloc_pagealloc_more_oob), KUNIT_CASE(krealloc_pagealloc_less_oob), + KUNIT_CASE(krealloc_uaf), KUNIT_CASE(kmalloc_oob_16), KUNIT_CASE(kmalloc_uaf_16), KUNIT_CASE(kmalloc_oob_in_memset), diff --git a/mm/slab_common.c b/mm/slab_common.c index 39d1a8ff9bb8..dad70239b54c 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1140,6 +1140,9 @@ static __always_inline void *__do_krealloc(const void *p, size_t new_size, void *ret; size_t ks; + if (likely(!ZERO_OR_NULL_PTR(p)) && !kasan_check_byte(p)) + return NULL; + ks = ksize(p); if (ks >= new_size) { -- 2.30.0.365.g02bc693789-goog