From nobody Wed Dec 24 18:00:37 2025 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (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 899697E562 for ; Wed, 24 Jan 2024 16:42:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706114547; cv=none; b=uZBxZS7Baah2dnAuVpCRjME7BNZSRAB40x25MDJU/AeGgVF8jd3p4JqpCiOv506BC/Fr5cJVHXwWBql03vuDuzR9w14bGhHZgJBSO/TB+OIU67SNI0Gdhy05FEuXcVFWAFCwoyseQ7glj7kenbuC49ZbNpDQ2Oadf5FINd3KCyA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706114547; c=relaxed/simple; bh=3gkbJDusbQAmzhaAVsHFUeUqAUKGRL4ctUUYeBa0mqE=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=CDQCJWRu9D+VbJ4X3+Aj9ef4WcdLFzGIKbrTCGR4nh76ga6YR18sM23T3AHZ8Cg+UTdN5jGWwLT5iRDIPcOStdr7TWl5Fk4ldymCLmckE+sJ3y6R3N5CNaO1G9t5DGFu0o36ix0q8F4tUgA2ofasO2X+Hlg1fxUGVXm1xse4zaE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--glider.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=OQ+30pWw; arc=none smtp.client-ip=209.85.128.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--glider.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OQ+30pWw" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-5ff82dc16e0so68535577b3.2 for ; Wed, 24 Jan 2024 08:42:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706114544; x=1706719344; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=m7Y5l6OToLybSucRHht2qJXpk8kuciDNbQY5osmgoqQ=; b=OQ+30pWwADGBxPwp174eCBWRgYyoSswXj9piky7Xu8jldgUIhyby49n1SmuH9pYWQ1 UZT4s2uRheLBckVMr0/HPV/EidS2o6SCpnrHLuPYEPFVNOhNuc/JBOliK7QS256/Wj/y lqFciAl1yttRxLd8KRsUdEbGU7q8xccjRPQacqlMNJotHLdHeS5I/aeuPVPXTAt7K2Cj wtgo6dkKAw8UaijsCTqGBsf7Dbq1n5T+Vfqxr2G6IHOIUvIMOfcx6BLfbd5SptmVgAw4 brs43r4xduQvPaIvd5+4IOu2PN3D1PV6nN4FTlXSCRSVplh9Qg6H9r8FhidInAhedotD NxAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706114544; x=1706719344; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=m7Y5l6OToLybSucRHht2qJXpk8kuciDNbQY5osmgoqQ=; b=c1JpLb9soasvDuZnZiOmM95cn1IAsi/vu2LkgXGvCqiY/GL5yVseGmsaGxwybZek4J Ev/eUcP52oK+kmAfZl4DpTYITGw7pyeNyeK/41AVOJMgDmq8pr6QlhRfit2p5MZaPdna 7B1d/G1vIyrY/+kwtsyPLZ+1hSWwFmkllffI/onaeYlb6/bON3oOh9LTLPD2o5O+He6Q b4eJV9Kf10bvJPdwvCRbj/C9II5baQT/W4WXaa+JAHJbistmZ2o7/Aw5mabQlbKqzmms fve1zb0iZxgrkEOIzWDlA5OJurpEhDCysIuTTVWCejI4xpjrlxMgRCIwoRLPh++Xkn2c JoSw== X-Gm-Message-State: AOJu0YzYnQp6nTjKmczwpGAgs3e9WxLcDAyMVgY3ffXTBpTlGUw3+L9x yQ/ZEFIsJzlV2e8Zb7Qq344//SfUksJQyaJ/oM3rLGteRH8riVYoCzKS1I0YlnKTQsX23h2Tt0Y JVw== X-Google-Smtp-Source: AGHT+IE8G4CSoHGmvsFg4U8Twsy6s+ghNL6n63NA7hAkz/CeB7MqCLzFD9amGXbO14msKZhvzjbQmeFXswY= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:ca56:4222:6893:5055]) (user=glider job=sendgmr) by 2002:a0d:d708:0:b0:5d4:263e:c819 with SMTP id z8-20020a0dd708000000b005d4263ec819mr360803ywd.8.1706114544464; Wed, 24 Jan 2024 08:42:24 -0800 (PST) Date: Wed, 24 Jan 2024 17:42:11 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240124164211.1141742-1-glider@google.com> Subject: [PATCH] mm: kmsan: remove runtime checks from kmsan_unpoison_memory() From: Alexander Potapenko To: glider@google.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, Marco Elver , Dmitry Vyukov , Ilya Leoshkevich , Nicholas Miehlbradt Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Similarly to what's been done in commit ff444efbbb9be ("kmsan: allow using __msan_instrument_asm_store() inside runtime"), it should be safe to call kmsan_unpoison_memory() from within the runtime, as it does not allocate memory or take locks. Remove the redundant runtime checks. This should fix false positives seen with CONFIG_DEBUG_LIST=3Dy when the non-instrumented lib/stackdepot.c failed to unpoison the memory chunks later checked by the instrumented lib/list_debug.c Also replace the implementation of kmsan_unpoison_entry_regs() with a call to kmsan_unpoison_memory(). Signed-off-by: Alexander Potapenko Cc: Marco Elver Cc: Dmitry Vyukov Cc: Ilya Leoshkevich Cc: Nicholas Miehlbradt Tested-by: Marco Elver --- mm/kmsan/hooks.c | 36 +++++++++++++----------------------- 1 file changed, 13 insertions(+), 23 deletions(-) diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 5d6e2dee5692a..8a990cbf6d670 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -359,6 +359,12 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int n= ents, } =20 /* Functions from kmsan-checks.h follow. */ + +/* + * To create an origin, kmsan_poison_memory() unwinds the stacks and store= s it + * into the stack depot. This may cause deadlocks if done from within KMSAN + * runtime, therefore we bail out if kmsan_in_runtime(). + */ void kmsan_poison_memory(const void *address, size_t size, gfp_t flags) { if (!kmsan_enabled || kmsan_in_runtime()) @@ -371,47 +377,31 @@ void kmsan_poison_memory(const void *address, size_t = size, gfp_t flags) } EXPORT_SYMBOL(kmsan_poison_memory); =20 +/* + * Unlike kmsan_poison_memory(), this function can be used from within KMS= AN + * runtime, because it does not trigger allocations or call instrumented c= ode. + */ void kmsan_unpoison_memory(const void *address, size_t size) { unsigned long ua_flags; =20 - if (!kmsan_enabled || kmsan_in_runtime()) + if (!kmsan_enabled) return; =20 ua_flags =3D user_access_save(); - kmsan_enter_runtime(); /* The users may want to poison/unpoison random memory. */ kmsan_internal_unpoison_memory((void *)address, size, KMSAN_POISON_NOCHECK); - kmsan_leave_runtime(); user_access_restore(ua_flags); } EXPORT_SYMBOL(kmsan_unpoison_memory); =20 /* - * Version of kmsan_unpoison_memory() that can be called from within the K= MSAN - * runtime. - * - * Non-instrumented IRQ entry functions receive struct pt_regs from assemb= ly - * code. Those regs need to be unpoisoned, otherwise using them will resul= t in - * false positives. - * Using kmsan_unpoison_memory() is not an option in entry code, because t= he - * return value of in_task() is inconsistent - as a result, certain calls = to - * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensure= s that - * the registers are unpoisoned even if kmsan_in_runtime() is true in the = early - * entry code. + * Version of kmsan_unpoison_memory() called from IRQ entry functions. */ void kmsan_unpoison_entry_regs(const struct pt_regs *regs) { - unsigned long ua_flags; - - if (!kmsan_enabled) - return; - - ua_flags =3D user_access_save(); - kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs), - KMSAN_POISON_NOCHECK); - user_access_restore(ua_flags); + kmsan_unpoison_memory((void *)regs, sizeof(*regs); } =20 void kmsan_check_memory(const void *addr, size_t size) --=20 2.43.0.429.g432eaa2c6b-goog