From nobody Wed Dec 31 08:32:43 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 037D7C4332F for ; Mon, 6 Nov 2023 20:10:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233045AbjKFUK4 (ORCPT ); Mon, 6 Nov 2023 15:10:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232927AbjKFUKl (ORCPT ); Mon, 6 Nov 2023 15:10:41 -0500 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41C7210C2 for ; Mon, 6 Nov 2023 12:10:38 -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=VrpDyLzZeYtu1H7+z0aR/HPyxv+dwo0N2+jHNRcNovg=; b=IRiR9duyySKTYMlcSCduunnoFku2ROSf7vVls3D3d5l3t64Tp6PJw5Tzev1W2QXnSS/iWi scQl4qOULKDYkIq8kuBLwHryMfjiAPS/Y+ufLRnA9LEHL20nZi55MDGuAm5yVuXtUNIc/i InULrYEGV1Mdxdx3Gw/YrKrgNHW65dM= 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 05/20] kasan: introduce kasan_mempool_unpoison_object Date: Mon, 6 Nov 2023 21:10:14 +0100 Message-Id: <6b096bcf531f457b13959ea99b1e270b96d5ca34.1699297309.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 Introduce and document a kasan_mempool_unpoison_object hook. This hook serves as a replacement for the generic kasan_unpoison_range that the mempool code relies on right now. mempool will be updated to use the new hook in one of the following patches. For now, define the new hook to be identical to kasan_unpoison_range. One of the following patches will update it to add stack trace collection. Signed-off-by: Andrey Konovalov --- include/linux/kasan.h | 31 +++++++++++++++++++++++++++++++ mm/kasan/common.c | 5 +++++ 2 files changed, 36 insertions(+) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 33387e254caa..c5fe303bc1c2 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -228,6 +228,9 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned = long ip); * bugs and reports them. The caller can use the return value of this func= tion * to find out if the allocation is buggy. * + * Before the poisoned allocation can be reused, it must be unpoisoned via + * kasan_mempool_unpoison_object(). + * * 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). @@ -241,6 +244,32 @@ static __always_inline bool kasan_mempool_poison_objec= t(void *ptr) return true; } =20 +void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long= ip); +/** + * kasan_mempool_unpoison_object - Unpoison a mempool slab allocation. + * @ptr: Pointer to the slab allocation. + * @size: Size to be unpoisoned. + * + * This function is intended for kernel subsystems that cache slab allocat= ions + * to reuse them instead of freeing them back to the slab allocator (e.g. + * mempool). + * + * This function unpoisons a slab allocation that was previously poisoned = via + * kasan_mempool_poison_object() without initializing its memory. For the + * tag-based modes, this function does not assign a new tag to the allocat= ion + * and instead restores the original tags based on the pointer value. + * + * 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). + */ +static __always_inline void kasan_mempool_unpoison_object(void *ptr, + size_t size) +{ + if (kasan_enabled()) + __kasan_mempool_unpoison_object(ptr, size, _RET_IP_); +} + /* * Unlike kasan_check_read/write(), kasan_check_byte() is performed even f= or * the hardware tag-based mode that doesn't rely on compiler instrumentati= on. @@ -301,6 +330,8 @@ static inline bool kasan_mempool_poison_object(void *pt= r) { return true; } +static inline void kasan_mempool_unpoison_object(void *ptr, size_t size) {} + static inline bool kasan_check_byte(const void *address) { return true; diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 087f93629132..033c860afe51 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -441,6 +441,11 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned= long ip) } } =20 +void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long= ip) +{ + kasan_unpoison(ptr, size, false); +} + bool __kasan_check_byte(const void *address, unsigned long ip) { if (!kasan_byte_accessible(address)) { --=20 2.25.1