From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3340693-1520824554-2-3478248453116339981 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='uk', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1520824554; b=N7lm7P7hRr3HACx751PBk5AYWPdfy8VSmh7YuwfRNoCFjZN AcA0oVCOy1qxnO6hyNjMcIA98Kj8ku4Yso6NoFjdDFb8OsVbgyrET0wCfuexBlTx CQRz9+eeo7D2WDquxxr8yor9bllO6MvfHFg98Na5D4bqYMCmtfBeXhQY5cT/cFBx /A3PNSp8sasCrm9ooL3b0tXwqCzwT3srDoADhF9kyz/HUW73/fq+HMJYytye1jf0 Xur2KTZGnCWdOyBNDiZjFtuAtuLIOtVHj3aW82li+sAekU61reS4945DCzKqqcRZ 2GdtDVO1uK+J1Lt2n6TsykjWIiTfxhTi+81F8lg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:content-transfer-encoding :mime-version:from:to:cc:date:message-id:subject:in-reply-to :sender:list-id; s=arctest; t=1520824554; bh=AcH9tCH/11YL7HD798a t7mvOPqwT1CUoY42OziFbsSI=; b=oGX92++rb3wBSayKV30ApEhVjLNwBRdr13m Trlq5GoquSMPCuRRonpMGvSzv+GnFfWx2+bLCU64OfwLL0Z2AOB0dFpch22E1mH3 viLCDEnWBoPuhqeZxDVd+SKILG+fi9QC9RSO3NIr9LSep/EG9LlrN6RIHrBF+vIX ibF1hykSdYcOo/etoQWHLlP3ZbTMj8PSlFpzhjcZDqoFnlM2LDq7zYfis9SpHUnu L0PV4qk3KXNt+TnLo+iV9DfkY6j85nOpkKH7jXqpL/A7L0koJ5phI6hF4cIj354G 1Uz9WcH1g6IEQOKDNtf88W7YpzmR5MFLm8x0IzYPH2aCtPpu4WA== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=decadent.org.uk header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=decadent.org.uk header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932843AbeCLDOw (ORCPT ); Sun, 11 Mar 2018 23:14:52 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41521 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932786AbeCLDHv (ORCPT ); Sun, 11 Mar 2018 23:07:51 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Chuck Ebbert" , "Richard W.M. Jones" , "Borislav Petkov" , "Thomas Gleixner" Date: Mon, 12 Mar 2018 03:06:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 15/76] x86/alternatives: Make optimize_nops() interrupt safe and synced In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.16.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 66c117d7fa2ae429911e60d84bf31a90b2b96189 upstream. Richard reported the following crash: [ 0.036000] BUG: unable to handle kernel paging request at 55501e06 [ 0.036000] IP: [] common_interrupt+0xb/0x38 [ 0.036000] Call Trace: [ 0.036000] [] ? add_nops+0x90/0xa0 [ 0.036000] [] apply_alternatives+0x274/0x630 Chuck decoded: " 0: 8d 90 90 83 04 24 lea 0x24048390(%eax),%edx 6: 80 fc 0f cmp $0xf,%ah 9: a8 0f test $0xf,%al >> b: a0 06 1e 50 55 mov 0x55501e06,%al 10: 57 push %edi 11: 56 push %esi Interrupt 0x30 occurred while the alternatives code was replacing the initial 0x90,0x90,0x90 NOPs (from the ASM_CLAC macro) with the optimized version, 0x8d,0x76,0x00. Only the first byte has been replaced so far, and it makes a mess out of the insn decoding." optimize_nops() is buggy in two aspects: - It's not disabling interrupts across the modification - It's lacking a sync_core() call Add both. Fixes: 4fd4b6e5537c 'x86/alternatives: Use optimized NOPs for padding' Reported-and-tested-by: "Richard W.M. Jones" Signed-off-by: Thomas Gleixner Cc: Richard W.M. Jones Cc: Chuck Ebbert Cc: Borislav Petkov Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1509031232340.15006@nanos Signed-off-by: Thomas Gleixner Signed-off-by: Ben Hutchings --- arch/x86/kernel/alternative.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -325,10 +325,15 @@ done: static void __init_or_module optimize_nops(struct alt_instr *a, u8 *instr) { + unsigned long flags; + if (instr[0] != 0x90) return; + local_irq_save(flags); add_nops(instr + (a->instrlen - a->padlen), a->padlen); + sync_core(); + local_irq_restore(flags); DUMP_BYTES(instr, a->instrlen, "%p: [%d:%d) optimized NOPs: ", instr, a->instrlen - a->padlen, a->padlen);