From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-549093-1518798793-2-3003802309840411595 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 0.001, 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='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='us-ascii' 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=1518798793; b=YB+P3Ssos9b6v2/msx7ksHax5GYDp9+djV8hn9Q473gnXN7 PfvyZXOV1DEGPlYbdFnb2WJb2L63hx1+xOOD/cXNcMC3iUNLTWXCRtJmKwF0wGQM rnqTx6tlxnYa5F/UBtE1c1+wzckI88YsA9E+kFakhP36xB1GyWyjN5YIi2sPBI/3 cJ6ZA0ruPWWB1JOiyx15zrkwsMacws7G1roSUCCq+OC/SOZcsDLtJQ+pBRoKhrRP Iqt68Wmxk/XmO3hNFS3i+6oF3hZMMQM2NowHjmrcToiumRrcEMkJ/fcr94HkNegl poqDnFV+YP7oW8QKXwsAV6RMB3YpNsxPL9L8eqA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to:sender :list-id; s=arctest; t=1518798793; bh=kT9dQKtRnKtX8xR8m02NvyVG6Q W+fYpJNeq6ZSUBkw8=; b=P0A0H31/Z3j0Z6tP2dqRRkzrEjVypDag36CgKKgzqJ tHcNqOI3CRqIIw17bWUDOqgc/AJT0Q0jNX3OQaiV9alBbhhTfv2dOsiuqvIVxeN3 07R0sPYI5lsWGEBI97kTvOD3bCEyyT/NEdP8+BeFXX4f8R5IRBH2a/F22sXnrly0 DaqpcsGdS04/fDcRYOMxl7Ml0sonkhMjKYZCwdMNTMqaqvIvLqMIabUVx09NHvrn aHfNAneuh/01iMVh2Lmq9LzGFwfnjVBbrrf5KLWSL7TmvVqEsVAwHfu4rzHVnJ6Y ng9cO6t8Gv8md3MEMVE+jlv+kVXt58/DoLIQTfGuJ4hg== ARC-Authentication-Results: i=1; mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; 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-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=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; 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-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=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032111AbeBPQc6 (ORCPT ); Fri, 16 Feb 2018 11:32:58 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:52498 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031831AbeBPQc5 (ORCPT ); Fri, 16 Feb 2018 11:32:57 -0500 Date: Fri, 16 Feb 2018 17:32:57 +0100 From: Greg Kroah-Hartman To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, Todd Kjos , Arve Hjonnevag , Greg Hackmann , stable@vger.kernel.org Subject: Re: [PATCH] staging: ashmem: Fix lockdep issue during llseek Message-ID: <20180216163257.GA7752@kroah.com> References: <20180213010125.174811-1-joelaf@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180213010125.174811-1-joelaf@google.com> User-Agent: Mutt/1.9.3 (2018-01-21) 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 Mon, Feb 12, 2018 at 05:01:25PM -0800, Joel Fernandes wrote: > ashmem_mutex create a chain of dependencies like so: > > (1) > mmap syscall -> > mmap_sem -> (acquired) > ashmem_mmap > ashmem_mutex (try to acquire) > (block) > > (2) > llseek syscall -> > ashmem_llseek -> > ashmem_mutex -> (acquired) > inode_lock -> > inode->i_rwsem (try to acquire) > (block) > > (3) > getdents -> > iterate_dir -> > inode_lock -> > inode->i_rwsem (acquired) > copy_to_user -> > mmap_sem (try to acquire) > > There is a lock ordering created between mmap_sem and inode->i_rwsem > causing a lockdep splat [2] during a syzcaller test, this patch fixes > the issue by unlocking the mutex earlier. Functionally that's Ok since > we don't need to protect vfs_llseek. > > [1] https://patchwork.kernel.org/patch/10185031/ > [2] https://lkml.org/lkml/2018/1/10/48 > > Cc: Todd Kjos > Cc: Arve Hjonnevag > Cc: Greg Hackmann > Cc: Greg Kroah-Hartman > Cc: stable@vger.kernel.org > Reported-by: syzbot+8ec30bb7bf1a981a2012@syzkaller.appspotmail.com > Signed-off-by: Joel Fernandes > --- > drivers/staging/android/ashmem.c | 15 +++++++-------- > 1 file changed, 7 insertions(+), 8 deletions(-) Please always properly version your patches, and put what changed below the --- line, so I have a hint as to which patch to apply. Documentation/SubmittingPatches has the full details of how to do this. Can you resend me the "latest" version of this patch, so I have a chance of getting it right? :) thanks, greg k-h