From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4209C433EF for ; Tue, 21 Sep 2021 20:13:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B310361038 for ; Tue, 21 Sep 2021 20:13:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233936AbhIUUO4 (ORCPT ); Tue, 21 Sep 2021 16:14:56 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:50794 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbhIUUOy (ORCPT ); Tue, 21 Sep 2021 16:14:54 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1632255204; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U0cT54wjFzwYV56IKeBKsvLuQnhMoza2aiMZO/77L1U=; b=c/I+9j7XlYYit/f+dzeRfOadmv+YowkHrnttT0o8abNF3RC+vJUCPcXeM9w/m7rXrZAEUv gdKamNjPTSeuOKen/7J8rTCSSndjv3pb54XuJVad5i2GUWSzIPcvAAGfTKaVNuAfx5szjG 8kQprbFn4ncDyB5tDRiLu64QMFW8XxE7zZuQxFhLHQJbmzrKffKtDrM5ePVgKEDKnTtXwU R6J7Yhx3FKydlih4Q3DzbHYo457i2IqDPsqtPxzhAXbOTpKdesX8OXKrVNYgJyo1kpdz/Q 05lzxCCgpRwufJmu7/eUPl45G5DteNTgQbWZ32Z1RIqUuwZ0sSfWyU0Rxk6tSQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1632255204; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=U0cT54wjFzwYV56IKeBKsvLuQnhMoza2aiMZO/77L1U=; b=52STx6QOv542bH3YxfmYQ7eQWh7POFCKqj0k2/aKvn/HFyv3DEwFENzCXju0Fh99+tuehz FGbSVBVOOziSRfCQ== To: Anders Roxell Cc: LKML , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Al Viro , Linus Torvalds , Tony Luck , Alexei Starovoitov , Peter Ziljstra , Song Liu , Daniel Borkmann Subject: Re: [patch V3 15/20] x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers to boolean In-Reply-To: References: <20210908130922.118265849@linutronix.de> <20210908132525.794334915@linutronix.de> Date: Tue, 21 Sep 2021 22:13:23 +0200 Message-ID: <871r5h7km4.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 21 2021 at 12:58, Anders Roxell wrote: > On Wed, 8 Sept 2021 at 15:30, Thomas Gleixner wrote: >> >> Now that copy_fpregs_to_sigframe() returns boolean the individual return >> codes in the related helper functions do not make sense anymore. Change >> them to return boolean success/fail. >> >> Signed-off-by: Thomas Gleixner > > When I build and boot (qemu_x86_64) a defconfig kernel on from todays > next tag next-20210921 I see the following segmentation fault > > 2021-09-21T10:11:45 <6>[ 1.622922] mount (89) used greatest stack > depth: 14384 bytes left > 2021-09-21T10:11:45 <6>[ 1.664760] EXT4-fs (sda): re-mounted. Opts: > (null). Quota mode: none. > 2021-09-21T10:11:45 <6>[ 1.691041] mkdir (92) used greatest stack > depth: 14312 bytes left > 2021-09-21T10:11:45 <6>[ 1.713201] mount (93) used greatest stack > depth: 13720 bytes left > 2021-09-21T10:11:46 Starting syslogd: /etc/init.d/rcS: line 12: 101 > Segmentation fault $i start > > > I did a bisection and found this as the faulty patch [1]. When I > revert this patch I can't see the issue. > > We noticed that function 'save_xstate_epilog()' changes the polarity > of its return code for one of the return statements, and for its only > caller. but not for the other return statement. > > I tried this patch and I couldn't see the segmentation fault. > > diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c > index 445c57c9c539..61eeebc04427 100644 > --- a/arch/x86/kernel/fpu/signal.c > +++ b/arch/x86/kernel/fpu/signal.c > @@ -104,7 +104,7 @@ static inline int save_xstate_epilog(void __user > *buf, int ia32_frame) > err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes)); > > if (!use_xsave()) > - return err; > + return !err; Oops. Good catch. Care to send a proper patch for this? Thanks, tglx