From nobody Wed Dec 31 08:33:58 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0D68C4332F for ; Mon, 6 Nov 2023 20:10:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232982AbjKFUKq (ORCPT ); Mon, 6 Nov 2023 15:10:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232686AbjKFUKk (ORCPT ); Mon, 6 Nov 2023 15:10:40 -0500 Received: from out-175.mta1.migadu.com (out-175.mta1.migadu.com [95.215.58.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2AA310C1 for ; Mon, 6 Nov 2023 12:10:37 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1699301436; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Hi9wxEG5hyOM24yVF5pvgyGm+UDfsaiMZW2KqzysWxs=; b=mSKMvKXcLKjjTcyMkClrC36gOqKSe1PvNKyag40bJ4xtUzbPDJFYH5kFaBHKeVRgaBbWYV GIZXX51aID/GYcIpaL4fQ+N0sAMZRrmnx9/AYcnXe7Vz4JkkXEyYOmwLRJOMKQdsT311zO FHVzZWec6HA/wWLZY3SvOuHIPVsbkv8= From: andrey.konovalov@linux.dev To: Marco Elver , Alexander Potapenko Cc: Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Evgenii Stepanov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH RFC 04/20] kasan: add return value for kasan_mempool_poison_object Date: Mon, 6 Nov 2023 21:10:13 +0100 Message-Id: <673406599a04fc9ea0111dac01ae9c84f9a01524.1699297309.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Andrey Konovalov Add a return value for kasan_mempool_poison_object that lets the caller know whether the allocation is affected by a double-free or an invalid-free bug. The caller can use this return value to stop operating on the object. Also introduce a check_page_allocation helper function to improve the code readability. Signed-off-by: Andrey Konovalov --- include/linux/kasan.h | 17 ++++++++++++----- mm/kasan/common.c | 21 ++++++++++----------- 2 files changed, 22 insertions(+), 16 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index bbf6e2fa4ffd..33387e254caa 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -212,7 +212,7 @@ static __always_inline void * __must_check kasan_kreall= oc(const void *object, return (void *)object; } =20 -void __kasan_mempool_poison_object(void *ptr, unsigned long ip); +bool __kasan_mempool_poison_object(void *ptr, unsigned long ip); /** * kasan_mempool_poison_object - Check and poison a mempool slab allocatio= n. * @ptr: Pointer to the slab allocation. @@ -225,16 +225,20 @@ void __kasan_mempool_poison_object(void *ptr, unsigne= d long ip); * without putting it into the quarantine (for the Generic mode). * * This function also performs checks to detect double-free and invalid-fr= ee - * bugs and reports them. + * bugs and reports them. The caller can use the return value of this func= tion + * to find out if the allocation is buggy. * * This function operates on all slab allocations including large kmalloc * allocations (the ones returned by kmalloc_large() or by kmalloc() with = the * size > KMALLOC_MAX_SIZE). + * + * Return: true if the allocation can be safely reused; false otherwise. */ -static __always_inline void kasan_mempool_poison_object(void *ptr) +static __always_inline bool kasan_mempool_poison_object(void *ptr) { if (kasan_enabled()) - __kasan_mempool_poison_object(ptr, _RET_IP_); + return __kasan_mempool_poison_object(ptr, _RET_IP_); + return true; } =20 /* @@ -293,7 +297,10 @@ static inline void *kasan_krealloc(const void *object,= size_t new_size, { return (void *)object; } -static inline void kasan_mempool_poison_object(void *ptr) {} +static inline bool kasan_mempool_poison_object(void *ptr) +{ + return true; +} static inline bool kasan_check_byte(const void *address) { return true; diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 69f4c66f0da3..087f93629132 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -244,7 +244,7 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *= object, return ____kasan_slab_free(cache, object, ip, true, init); } =20 -static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip) +static inline bool check_page_allocation(void *ptr, unsigned long ip) { if (!kasan_arch_is_ready()) return false; @@ -259,17 +259,14 @@ static inline bool ____kasan_kfree_large(void *ptr, u= nsigned long ip) return true; } =20 - /* - * The object will be poisoned by kasan_poison_pages() or - * kasan_mempool_poison_object(). - */ - return false; } =20 void __kasan_kfree_large(void *ptr, unsigned long ip) { - ____kasan_kfree_large(ptr, ip); + check_page_allocation(ptr, ip); + + /* The object will be poisoned by kasan_poison_pages(). */ } =20 void * __must_check __kasan_slab_alloc(struct kmem_cache *cache, @@ -419,7 +416,7 @@ void * __must_check __kasan_krealloc(const void *object= , size_t size, gfp_t flag return ____kasan_kmalloc(slab->slab_cache, object, size, flags); } =20 -void __kasan_mempool_poison_object(void *ptr, unsigned long ip) +bool __kasan_mempool_poison_object(void *ptr, unsigned long ip) { struct folio *folio; =20 @@ -432,13 +429,15 @@ void __kasan_mempool_poison_object(void *ptr, unsigne= d long ip) * KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc. */ if (unlikely(!folio_test_slab(folio))) { - if (____kasan_kfree_large(ptr, ip)) - return; + if (check_page_allocation(ptr, ip)) + return false; kasan_poison(ptr, folio_size(folio), KASAN_PAGE_FREE, false); + return true; } else { struct slab *slab =3D folio_slab(folio); =20 - ____kasan_slab_free(slab->slab_cache, ptr, ip, false, false); + return !____kasan_slab_free(slab->slab_cache, ptr, ip, + false, false); } } =20 --=20 2.25.1