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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 016F8C4332F for ; Mon, 15 Nov 2021 18:24:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF6C563423 for ; Mon, 15 Nov 2021 18:24:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240823AbhKOS04 (ORCPT ); Mon, 15 Nov 2021 13:26:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:46730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238178AbhKORdi (ORCPT ); Mon, 15 Nov 2021 12:33:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 88D7863248; Mon, 15 Nov 2021 17:21:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636996900; bh=XmzqHL0Z0tJSw6FXl0JzN3xJCCpGMGmK9Cp/EP+0nkA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KaoACGz5jQJjuatCI6RAlwwv5jgVkNYzVfbnzYLbWDmvyE5Lf0UOAVflrNkH1FLdd fE+jUJbebc+g7OKjcK/tlLLtHxqsFnvo3mARkxFnzORfxnkQw52OHACfH+AkDazLBK EbPMzMpTIhJH2LyTXyn7L6cqWcCBL3oycKZIiYKI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yoshinori Sato , Rich Felker , linux-sh@vger.kernel.org, "Eric W. Biederman" , Sasha Levin Subject: [PATCH 5.4 307/355] signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL) Date: Mon, 15 Nov 2021 18:03:51 +0100 Message-Id: <20211115165323.653076217@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165313.549179499@linuxfoundation.org> References: <20211115165313.549179499@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric W. Biederman [ Upstream commit ce0ee4e6ac99606f3945f4d47775544edc3f7985 ] Today the sh code allocates memory the first time a process uses the fpu. If that memory allocation fails, kill the affected task with force_sig(SIGKILL) rather than do_group_exit(SIGKILL). Calling do_group_exit from an exception handler can potentially lead to dead locks as do_group_exit is not designed to be called from interrupt context. Instead use force_sig(SIGKILL) to kill the userspace process. Sending signals in general and force_sig in particular has been tested from interrupt context so there should be no problems. Cc: Yoshinori Sato Cc: Rich Felker Cc: linux-sh@vger.kernel.org Fixes: 0ea820cf9bf5 ("sh: Move over to dynamically allocated FPU context.") Link: https://lkml.kernel.org/r/20211020174406.17889-6-ebiederm@xmission.com Signed-off-by: Eric W. Biederman Signed-off-by: Sasha Levin --- arch/sh/kernel/cpu/fpu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/sh/kernel/cpu/fpu.c b/arch/sh/kernel/cpu/fpu.c index ae354a2931e7e..fd6db0ab19288 100644 --- a/arch/sh/kernel/cpu/fpu.c +++ b/arch/sh/kernel/cpu/fpu.c @@ -62,18 +62,20 @@ void fpu_state_restore(struct pt_regs *regs) } if (!tsk_used_math(tsk)) { - local_irq_enable(); + int ret; /* * does a slab alloc which can sleep */ - if (init_fpu(tsk)) { + local_irq_enable(); + ret = init_fpu(tsk); + local_irq_disable(); + if (ret) { /* * ran out of memory! */ - do_group_exit(SIGKILL); + force_sig(SIGKILL); return; } - local_irq_disable(); } grab_fpu(regs); -- 2.33.0