From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f197.google.com (mail-il1-f197.google.com [209.85.166.197]) (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 416C8139D for ; Sun, 25 Feb 2024 01:50:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708825832; cv=none; b=cnJCPSi+UpLPBnn6yPuCLjAZg+RrUrnfjhy6VNo8Y9BynYTkMhb38EyNQoJMmOM4UX6W1g431rB3u9t80inEsJPbtV3qZFvh7kSdXx4iZO7CFxrqoK2WsskURGIefDCd0UihyyMJs4pzrE5L3vKl84Ku9dL/rZq19GWC/Us5oDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708825832; c=relaxed/simple; bh=Rz+jTzPeC9WLQNhTavEN1Oc8VP0JIfOQuV7w/Py+Z+w=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=LpJpcbAEvuZAz+iinKDtz/PA5A6Hk6ieT4HcidVNbRIxOWwkmX+Bt7lL73Gk9hnwhUCCOYbqfqgK7bOol/i4dRFUUvRPLEbra/Ch9dGdNz3A++yK0ApFweP66WImMS4JpJl+3X1t9WIeS2pR6Kw5cK6Ep65ikhQFPNakclagHNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.166.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-il1-f197.google.com with SMTP id e9e14a558f8ab-363b161279aso19815975ab.1 for ; Sat, 24 Feb 2024 17:50:30 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708825829; x=1709430629; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=t8WDBR/xUlcpd6GklJKTEb6zPyxzfXbVEJD4CBbyppY=; b=rUecpSg3BwnInDOGD6W48pRtVU+lBdUOlQzhTYKZ0A/EgvC+I8ypPRFJwGGpnHB6KY 8zvrs1PQfRZdRPbat3o2UJ8nJWbXPwGBP7lUyaeH+5ZSp5q84Na9NFjjQdQXiBL6mN8d T0asGbNdHrZh5JefE8eGXOyS50FwmYNiUyIRAZ8YaKT+2VWzFPAOMVf+KcVwjfzOB6aB qyAc3Gp3OqV3F6tOzTfRrjN6+Qb1FEuEP/M4x6TNo/DTvq1CLkA+3dXmJpTsgSpcI09i QQhJReNHEAG1rOy4iPFYgFWBvRIdEOfMX89SJZdRtncM3Bf7A58wRvsH7bEwlTp+PIHM Sl1Q== X-Gm-Message-State: AOJu0YxtbxdqLOPFmgZvqly9COUXpe+V3xdAB+LDGq2QPMlaXeYPeOQp q9TQ0vmJrR+N0U9xuPq9K/b/OEYSjkO6Ri8rRR3MD7Em+20S8h2QfkggqKRrAJMgYRAZ6SHBsut 4Udl/7urBkbdp1mvGtrywhXLRjJs+XAZGzFyuji7fT0ozu/8VHmEJbqJPjA== X-Google-Smtp-Source: AGHT+IGstkiZBVvC/Xqi0K434tLpOWB6QwC4pM0JsVcK9NwlX4NYOsSc7zY2T2kE+h5wD68Dw322R7ymfSAhXiWBUL7NWTXGS7MQ Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:1e05:b0:365:1846:bd5a with SMTP id g5-20020a056e021e0500b003651846bd5amr234676ila.5.1708825829418; Sat, 24 Feb 2024 17:50:29 -0800 (PST) Date: Sat, 24 Feb 2024 17:50:29 -0800 In-Reply-To: <000000000000fd588e060de27ef4@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <0000000000008bb08806122b04ca@google.com> Subject: Re: [syzbot] Re: [syzbot] [virtualization?] KMSAN: uninit-value in virtqueue_add (4) From: syzbot To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org. *** Subject: Re: [syzbot] [virtualization?] KMSAN: uninit-value in virtqueue_add (4) Author: penguin-kernel@i-love.sakura.ne.jp #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h index cc6b8e087192..f13bba3a9dab 100644 --- a/arch/x86/include/asm/page_64.h +++ b/arch/x86/include/asm/page_64.h @@ -58,7 +58,16 @@ static inline void clear_page(void *page) : "cc", "memory", "rax", "rcx"); } +#ifdef CONFIG_KMSAN +/* Use of non-instrumented assembly version confuses KMSAN. */ +void *memcpy(void *to, const void *from, __kernel_size_t len); +static inline void copy_page(void *to, void *from) +{ + memcpy(to, from, PAGE_SIZE); +} +#else void copy_page(void *to, void *from); +#endif #ifdef CONFIG_X86_5LEVEL /* diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 5d6e2dee5692..0b09daa188ef 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -359,6 +359,12 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int nents, } /* Functions from kmsan-checks.h follow. */ + +/* + * To create an origin, kmsan_poison_memory() unwinds the stacks and stores 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); +/* + * Unlike kmsan_poison_memory(), this function can be used from within KMSAN + * runtime, because it does not trigger allocations or call instrumented code. + */ void kmsan_unpoison_memory(const void *address, size_t size) { unsigned long ua_flags; - if (!kmsan_enabled || kmsan_in_runtime()) + if (!kmsan_enabled) return; ua_flags = 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); /* - * Version of kmsan_unpoison_memory() that can be called from within the KMSAN - * runtime. - * - * Non-instrumented IRQ entry functions receive struct pt_regs from assembly - * code. Those regs need to be unpoisoned, otherwise using them will result in - * false positives. - * Using kmsan_unpoison_memory() is not an option in entry code, because the - * return value of in_task() is inconsistent - as a result, certain calls to - * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures 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 = 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)); } void kmsan_check_memory(const void *addr, size_t size)