From nobody Thu Oct 2 07:46:29 2025 Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80131289821 for ; Fri, 19 Sep 2025 14:58:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758293884; cv=none; b=Qioi8Zo3VM9p6r9n528LE2FiRcXAoDmCGSMDUcbAOrJ53CniBQ97YWZbCDSl93r7LuR/yHmkhym+VI9BesMYJuPkVXFzb8EhmNCHd8pGKaz/5x9ZSBquTLJbeREr8osUDgGtZMUO15Y+f8qOGDOeVZxaZt+/WNxiwVUf9Oz0bYk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758293884; c=relaxed/simple; bh=egRlU8I8cap/vMG/cP8j3cYqgKLkvNE8Tghmz+aDQ8U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ACUZzq1Ecnh3QPbTvA6ARJ6J+TKZBDK/m0F6ZeuwDlQ9Yo4oXX/1lo36NqRHxtO4YO5l/S5PKohibaFVrYroOaWlzECb50jxeRMTMmwZ+s3dN5cEd7Laf7RjBdn/2UgYtJAtVWoAEegbbuoeqeJqpvdzPch4YMyBA2aSudcUGkI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=JdRqnUvr; arc=none smtp.client-ip=209.85.128.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JdRqnUvr" Received: by mail-wm1-f43.google.com with SMTP id 5b1f17b1804b1-45f2c5ef00fso17835915e9.1 for ; Fri, 19 Sep 2025 07:58:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1758293880; x=1758898680; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Iux7tJA7Iu45JzwDlqqn3NczB+xQmLnfn/+UUn4bsic=; b=JdRqnUvryAa6smB7nKg6KARTl+190Tbrk5xt77sgdnc30u1kPjHdigY4wD/JwYzoDb 5z3IIcR7ZkVks8kC5AAG1Iqn4hAbuaECNrauHnQpuOD4+1dV/raCWWK5lkli53zbg5GR CqmAZUSs6sl3IrGkbWAfn62HYiOkDFVE1gAcssm0LqymrHOv30FeVMHYQuODs9IptO6v 4/dnn7Zew7lTMqZId4aqOpiKMTswQ3IdU6zQAO8OKCqug/XcIY/bDooDA9qmfUltiIRJ e6hLXCKbYgNHrEtORzEekJ+HMok1ATD03jsh57QBxePhlNmhfGK+6vOdf54OIzDSFqGa FlpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758293880; x=1758898680; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Iux7tJA7Iu45JzwDlqqn3NczB+xQmLnfn/+UUn4bsic=; b=aEAZmaGE8eJ1fbLJRXVTTGF/ivZT38A68onYiKsoO5POtQhWPcfG5WUnWOylOGkH/9 a9yjIlExfn9o3X7EyREdRyVYhcEVKXexNawfpgs9AfJdr2yF+W+Ux163Y/L+M7jEzDqK SPk/F5hsaK7KHJ7ZDttU0sSLe9zPpVFE5FLMVOl6GQ/AVTci7U3PyRXH0mdy5oeQ8P0y I46/yiOV6JtoilF6TxCHE4cx02AcsKrh4pzz3c29yKrjd/srNW+zC7R/GTH6J0JwbUId 87tp6YcDPlTP4IIvRQAiD/Ukxz1lixhHqt/Chi1+vwiUpN0nVCmpbBOR+b5cuLuSmwHm WHNQ== X-Forwarded-Encrypted: i=1; AJvYcCVblyJNGwUFDOfYq8aTiUJdHgnJ39NEIiyCZSd+5KeIEdDAhWPm3dazB0S7VcvY+SU59O4Va7Env6xtBis=@vger.kernel.org X-Gm-Message-State: AOJu0YzgWx3yCCv5lpTPL+2TB5RJYs4emCbXOBS/i5XtIiWIg9rFqs32 KKp2C09CteaQtetpMsQqn8CVM7lHPa1JHRJAgx9NgZsMsloaxSGLiaoB X-Gm-Gg: ASbGnctMAVvbkDx0dJQX4/92ncdPwGFzR/t3Jy4FGaGR8wHpczojW4T00CxO9wMzTKq l6q9ARw2tqeh3R99uUzFQruIL59rvckh5T1TvwYjuDpqGk5iSoaMcQelI/2tDlFSobwlAVQoOL2 o/i5Emu4jY7aawDHn9+2M6mZLdtswjN0KAdGU1PtQ/TAd5ypw2tH5RSYrVH0vTSCUThMFdGY4Fb 0T3lxDw8X0nx2/dqkqP7qTwPkymLvFBtklFKlgahUcB9EdybbI2jTZyOq7cDluXleluZ6eyVvdF Hvchqnwn1WD0P7YmaF1jNLgNlYKwlxXCTwmbPaz2mbcZlykTw0ENwR73kRuYJYiSSGkD/dF0uj/ lfayuA7/nKr1sUC+ZqOmJIOzL1PH06i4oDwWf2+4A6EHA8d62n7vNqT1gX4dPCQtLDMfKC64Zg/ LOf5Myg+lOV48qLA0= X-Google-Smtp-Source: AGHT+IE+XK5nD+9hANJoxYPRSlTs9xbOKfixXYZia7lhztTHnoAksXT/1nQcAsPiiouWjOFFkGLQJg== X-Received: by 2002:a05:600c:b8d:b0:45d:e326:96fb with SMTP id 5b1f17b1804b1-467ef72d771mr33033965e9.30.1758293879733; Fri, 19 Sep 2025 07:57:59 -0700 (PDT) Received: from xl-nested.c.googlers.com.com (124.62.78.34.bc.googleusercontent.com. [34.78.62.124]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3ee0fbc7188sm8551386f8f.37.2025.09.19.07.57.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Sep 2025 07:57:59 -0700 (PDT) From: Ethan Graham To: ethangraham@google.com, glider@google.com Cc: andreyknvl@gmail.com, andy@kernel.org, brauner@kernel.org, brendan.higgins@linux.dev, davem@davemloft.net, davidgow@google.com, dhowells@redhat.com, dvyukov@google.com, elver@google.com, herbert@gondor.apana.org.au, ignat@cloudflare.com, jack@suse.cz, jannh@google.com, johannes@sipsolutions.net, kasan-dev@googlegroups.com, kees@kernel.org, kunit-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lukas@wunner.de, rmoar@google.com, shuah@kernel.org, sj@kernel.org, tarasmadan@google.com Subject: [PATCH v2 01/10] mm/kasan: implement kasan_poison_range Date: Fri, 19 Sep 2025 14:57:41 +0000 Message-ID: <20250919145750.3448393-2-ethan.w.s.graham@gmail.com> X-Mailer: git-send-email 2.51.0.470.ga7dc726c21-goog In-Reply-To: <20250919145750.3448393-1-ethan.w.s.graham@gmail.com> References: <20250919145750.3448393-1-ethan.w.s.graham@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Ethan Graham Introduce a new helper function, kasan_poison_range(), to encapsulate the logic for poisoning an arbitrary memory range of a given size, and expose it publically in . This is a preparatory change for the upcoming KFuzzTest patches, which requires the ability to poison the inter-region padding in its input buffers. No functional change to any other subsystem is intended by this commit. Signed-off-by: Ethan Graham Reviewed-by: Alexander Potapenko --- PR v1: - Enforce KASAN_GRANULE_SIZE alignment for the end of the range in kasan_poison_range(), and return -EINVAL when this isn't respected. --- --- include/linux/kasan.h | 11 +++++++++++ mm/kasan/shadow.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 890011071f2b..cd6cdf732378 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -102,6 +102,16 @@ static inline bool kasan_has_integrated_init(void) } =20 #ifdef CONFIG_KASAN + +/** + * kasan_poison_range - poison the memory range [@addr, @addr + @size) + * + * The exact behavior is subject to alignment with KASAN_GRANULE_SIZE, def= ined + * in : if @start is unaligned, the initial partial gran= ule + * at the beginning of the range is only poisoned if CONFIG_KASAN_GENERIC= =3Dy. + */ +int kasan_poison_range(const void *addr, size_t size); + void __kasan_unpoison_range(const void *addr, size_t size); static __always_inline void kasan_unpoison_range(const void *addr, size_t = size) { @@ -402,6 +412,7 @@ static __always_inline bool kasan_check_byte(const void= *addr) =20 #else /* CONFIG_KASAN */ =20 +static inline int kasan_poison_range(const void *start, size_t size) { ret= urn 0; } static inline void kasan_unpoison_range(const void *address, size_t size) = {} static inline void kasan_poison_pages(struct page *page, unsigned int orde= r, bool init) {} diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index d2c70cd2afb1..7faed02264f2 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -147,6 +147,40 @@ void kasan_poison(const void *addr, size_t size, u8 va= lue, bool init) } EXPORT_SYMBOL_GPL(kasan_poison); =20 +int kasan_poison_range(const void *addr, size_t size) +{ + uintptr_t start_addr =3D (uintptr_t)addr; + uintptr_t head_granule_start; + uintptr_t poison_body_start; + uintptr_t poison_body_end; + size_t head_prefix_size; + uintptr_t end_addr; + + if ((start_addr + size) % KASAN_GRANULE_SIZE) + return -EINVAL; + + end_addr =3D ALIGN_DOWN(start_addr + size, KASAN_GRANULE_SIZE); + if (start_addr >=3D end_addr) + return -EINVAL; + + head_granule_start =3D ALIGN_DOWN(start_addr, KASAN_GRANULE_SIZE); + head_prefix_size =3D start_addr - head_granule_start; + + if (IS_ENABLED(CONFIG_KASAN_GENERIC) && head_prefix_size > 0) + kasan_poison_last_granule((void *)head_granule_start, + head_prefix_size); + + poison_body_start =3D ALIGN(start_addr, KASAN_GRANULE_SIZE); + poison_body_end =3D ALIGN_DOWN(end_addr, KASAN_GRANULE_SIZE); + + if (poison_body_start < poison_body_end) + kasan_poison((void *)poison_body_start, + poison_body_end - poison_body_start, + KASAN_SLAB_REDZONE, false); + return 0; +} +EXPORT_SYMBOL(kasan_poison_range); + #ifdef CONFIG_KASAN_GENERIC void kasan_poison_last_granule(const void *addr, size_t size) { --=20 2.51.0.470.ga7dc726c21-goog