From nobody Sat Feb 7 19:41:02 2026 Received: from fhigh8-smtp.messagingengine.com (fhigh8-smtp.messagingengine.com [103.168.172.159]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D0BAC14A85 for ; Wed, 27 Mar 2024 06:13:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.159 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711520040; cv=none; b=jrNlVuL0/ZvDr38j3YFcd8Wi9Y50ZJv9Mu3WgDq47pJldKyZdY5sl35dsHrmWD3r0dHc4oC7z8TzUkSLZFwAnW9uhRtVcxsPfedxzQZYfbRDnDb5tSJPmPjKPSgcAPe+dYUpM6/PeRUtXLaGle/kC0HqYAfJW8CUQWtmgwO1lKE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711520040; c=relaxed/simple; bh=Z/t6oJU1Jq9ue+NRMzPbPR6p5EXRueXM4V3RRGGWG7k=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=ZeS8XG57adCnCRIKJGHhwE0QP4rfMo0tv6QdXEi4yikRxIzQKwIkcpab0cqkPCrQ70TuEka9LGavBZ3tE4NMX3tUT+v7GyG5stLWYurNYD3oP01txxUstem8f1Q9/aQjCfOMQx/2R1QnwFhhEJVvN33au7bgF3YrnQwr8CcRaDY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=fastmail.com; spf=pass smtp.mailfrom=fastmail.com; dkim=pass (2048-bit key) header.d=fastmail.com header.i=@fastmail.com header.b=fxABGrYa; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=x8VgCAB2; arc=none smtp.client-ip=103.168.172.159 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=fastmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fastmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fastmail.com header.i=@fastmail.com header.b="fxABGrYa"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="x8VgCAB2" Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailfhigh.nyi.internal (Postfix) with ESMTP id C98CF11400EC; Wed, 27 Mar 2024 02:13:57 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute3.internal (MEProxy); Wed, 27 Mar 2024 02:13:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastmail.com; h= cc:cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:message-id:mime-version:reply-to:subject:subject:to :to; s=fm2; t=1711520037; x=1711606437; bh=L8pGfRNbp7RCkrkxlFARY zS97IZ7JZRhum3Xf3Y6QJk=; b=fxABGrYah/lfTugzx6Z0ngEyOKWRtWYzw2pW/ oDhWOX9QSMk2VfcidduJHKIyV01zJ73f1uRLCql5WsrJwSSkQFWm7drJk3tIngiL 0mfL8EuvOafXILend5O0FzOnhhFBFo/r1nIwroaV4MtTS5lGPzaUi22mPFmrOpq4 w9ICMO9Ey00G91i2LJW2sAJOQobTVAnlbaULScXaO1XsmhfgUXf7PVtDHnLZFX0/ SraxSI+JgiiE0ZrX1dSpCjkG8AFtmcEv+u6GbFo/uGcB+maFKO91mbirP+67xBTr 7nYSgrRJ47+ONmUUPnQ18Tz9RcmmNjFV/F/6uVMpqrLinfFNA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:message-id:mime-version:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; t=1711520037; x=1711606437; bh=L8pGfRNbp7RCkrkxlFARYzS97IZ7 JZRhum3Xf3Y6QJk=; b=x8VgCAB2jgsbdijfdu2/B8BeuIbsrgzrgafUkHpBWgGa sXNVQ8vwBNYs9It0J8tAytS2ywlAkPO2Nvzz4ke5U3x+5KZtSDyXsHaemLZPkoNB uETABOwVA8CUCQoeAmwMM2/TB1Sy5kO/gRS4A0IPhgeNf4+uCCgUGeC14XrLz55T DRRP1xbL1jcIwwO7MvTbLR+uA2wDr3sjAyzbNYTLlrEs+rufyxA64rWGx2cfhXFn d82QmU0htYWo2whOIF9KvS85/mtNxVjPE3ECREBK9XPhB7C5CIPxja7yQuOvbN68 xpCLhRlkrqncv7TveFY5mWD0dlH0XUczsEkkBQF3/w== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvledruddugedgleefucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkofgggfestdekredtredttdenucfhrhhomhepufhtvghfrghn ucfqkdftvggrrhcuoehsohhrvggrrhesfhgrshhtmhgrihhlrdgtohhmqeenucggtffrrg htthgvrhhnpeeugfejveekgffhgfegvdetgfegvdekieffvefhiedugeefuedvieekieev heeuheenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpe hsohhrvggrrhesfhgrshhtmhgrihhlrdgtohhm X-ME-Proxy: Feedback-ID: i84414492:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 27 Mar 2024 02:13:57 -0400 (EDT) From: Stefan O'Rear To: linux-riscv@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-kernel@vger.kernel.org Cc: Stefan O'Rear Subject: [PATCH] riscv: process: Fix kernel gp leakage Date: Wed, 27 Mar 2024 02:12:58 -0400 Message-Id: <20240327061258.2370291-1-sorear@fastmail.com> X-Mailer: git-send-email 2.40.1 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" childregs represents the registers which are active for the new thread in user context. For a kernel thread, childregs->gp is never used since the kernel gp is not touched by switch_to. For a user mode helper, the gp value can be observed in user space after execve or possibly by other means. Fixes: 7db91e57a0ac ("RISC-V: Task implementation") Signed-off-by: Stefan O'Rear --- arch/riscv/kernel/process.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 92922dbd5b5c..51042f48da17 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -27,8 +27,6 @@ #include #include =20 -register unsigned long gp_in_global __asm__("gp"); - #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_T= ASK) #include unsigned long __stack_chk_guard __read_mostly; @@ -207,7 +205,6 @@ int copy_thread(struct task_struct *p, const struct ker= nel_clone_args *args) if (unlikely(args->fn)) { /* Kernel thread */ memset(childregs, 0, sizeof(struct pt_regs)); - childregs->gp =3D gp_in_global; /* Supervisor/Machine, irqs on: */ childregs->status =3D SR_PP | SR_PIE; =20 --=20 2.40.1