From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2341778-1520526731-2-7261546042362535020 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, FREEMAIL_FORGED_FROMDOMAIN 0.249, FREEMAIL_FROM 0.001, HEADER_FROM_DIFFERENT_DOMAINS 0.25, 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='com', 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=1520526731; b=L+ZabJmPxTZ9Nv2PDNUvcYVIk6sI2ghDQskGtubf5uEgjcm 0F457TPDpejb368YcuDbkShbjld7y1DPkM6/7PsKhL7D+L7MJdgzpUrPL/oR3xxU XKAxSdp7R+gKgef9dIj2nysnYDJbO8Il9DA21NK/4BtFb3YmrnqGVl8qOcAG+vtE M9y4kVxmu56bYnjb5HMXaQGyNxWKwHN5kBrGgMEZPgCvDMEz5HO+Y6FuupBiR44G LOyZHwMGgXa1PXMbFGgRw90j7WTayhwvsp5ubQOxHVBAQ/hF1KdPei8N3or/9t/y spSo06etOF23EmdGUcERWVnIyq2jl1WBIqEIjEQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=subject:to:cc:references:from:message-id :date:mime-version:in-reply-to:content-type :content-transfer-encoding:sender:list-id; s=arctest; t= 1520526731; bh=gH4602uLCZDLfMpIbylChUhbCyxK1CyBRjeSgAAniz4=; b=O e/9fSo8R7LJMhBf6Otch5VTRBa8Bu1MgCYbjnO5WzzfobSgWT59iMqlYcJOHmWgg 0SFZTCv6aqyiGKsccEu2pzz9aanJIeZbQAKCK+xhFRx31J6hl8E/Qqr3YDbdOjpK N6YziceFSRWwVHFzbPyjyqqtgDoZjh91+A8W4vLjkYPw14pv9C64TkESQvT/FlCp qqi+cP72DcIqSzaejSrbyowyPSJ1PON5zWQPcdd3PfzQ9Dzmn1BDuRaLJCpHHmJ7 mfGM2n5tShp6D47xym2210vZpZdPBi0VZ1sas66ElYbJv5fknb4SB3Ds98BbYE+m 3Zirwsv8LDMxb8g/KeyZA== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=pass (2048-bit rsa key sha256) header.d=gmail.com header.i=@gmail.com header.b=tVoGPoRR x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=20161025; dmarc=pass (p=none,has-list-id=yes,d=none) header.from=gmail.com; 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-google-dkim=pass (2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=SqMfUZ4s; 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=gmail.com header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=pass (2048-bit rsa key sha256) header.d=gmail.com header.i=@gmail.com header.b=tVoGPoRR x-bits=2048 x-keytype=rsa x-algorithm=sha256 x-selector=20161025; dmarc=pass (p=none,has-list-id=yes,d=none) header.from=gmail.com; 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-google-dkim=pass (2048-bit rsa key) header.d=1e100.net header.i=@1e100.net header.b=SqMfUZ4s; 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=gmail.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933560AbeCHQbw (ORCPT ); Thu, 8 Mar 2018 11:31:52 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:41072 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754612AbeCHQbu (ORCPT ); Thu, 8 Mar 2018 11:31:50 -0500 X-Google-Smtp-Source: AG47ELt2iljdQDTIsm9+2urWI7dPtMoa9P66FGOqm/rEBv8icKdhUhF9gcwvYdZMIpoShoMaBcefSg== Subject: Re: [PATCH] net: xfrm: use preempt-safe this_cpu_read() in ipcomp_alloc_tfms() To: Herbert Xu , Greg Hackmann Cc: Steffen Klassert , "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20180307192416.233202-1-ghackmann@google.com> <20180308073328.GA8111@gondor.apana.org.au> From: Eric Dumazet Message-ID: Date: Thu, 8 Mar 2018 08:31:47 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180308073328.GA8111@gondor.apana.org.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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: On 03/07/2018 11:33 PM, Herbert Xu wrote: > On Wed, Mar 07, 2018 at 11:24:16AM -0800, Greg Hackmann wrote: >> f7c83bcbfaf5 ("net: xfrm: use __this_cpu_read per-cpu helper") added a >> __this_cpu_read() call inside ipcomp_alloc_tfms(). Since this call was >> introduced, the rules around per-cpu accessors have been tightened and >> __this_cpu_read() cannot be used in a preemptible context. >> >> syzkaller reported this leading to the following kernel BUG while >> fuzzing sendmsg: > > How about reverting f7c83bcbfaf5 instead? > > Thanks, > Because that would not be nice. this_cpu_read() is faster than going through raw_smp_processor_id() and per_cpu_ptr()