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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8DEBECAAD5 for ; Tue, 30 Aug 2022 19:40:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230117AbiH3Tk5 (ORCPT ); Tue, 30 Aug 2022 15:40:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229565AbiH3Tkz (ORCPT ); Tue, 30 Aug 2022 15:40:55 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E38AB6B15D for ; Tue, 30 Aug 2022 12:40:54 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id z3-20020a17090abd8300b001fd803e34f1so10381993pjr.1 for ; Tue, 30 Aug 2022 12:40:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=cmkGTb9L9OeIMFxD3jKQUsg9TEkzwU9aSjE2Dw5vIEQ=; b=pE4Bx71pvd9dZKRF5z6T8Pt+bB46qQGtd9GcQDH2oAD1s76fa9WKjAuSmWyzPWGQpG FNbMF1rYoivPT1f8QXiYqZ+1HjEdCPv3zARTVSchZnowgeH7pmJWpqcu786U63xjebHh j/mnY4Nn33R/UydBsSBPRHKotcLndCHiknF7gSjmqe60n71QICcKqNrXcat1K0VxOnO+ c6oUjhHwUyUQUqan6gHFT6OrfVs6lupH8rxh4NVVFwKLjCj/Ko/B0MyeyqHq5D6jX3vT JdpcEoIAEwEawrh++3bTY7tivyd1iaD7bOYV+R6BUulsRnSyM2hduVBNyn0eCeXqyfKh wyPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=cmkGTb9L9OeIMFxD3jKQUsg9TEkzwU9aSjE2Dw5vIEQ=; b=Qm1L2O0E2Pt36B1Md3M3NkCOdeZi3Ezbhtbuw0P8skjWxA/JNTstuIFgmQrx6tcUEe n46pjB1G+NscpD4G3+nWWtUdSluSpPabXiVmiMqdsoiUdHWEUvCYfWOswAlTJDuIlpM1 kKDXINNVqIB2VEJwtk5ouGe+bDWe/bLcVzO+njchkecdXQA+e1TN2wS6oxyQZZDQBLHU MXiW4tYFRmEyE+qS3QheXOzPaE8D4cyTWVa+ea37IeAiKdVWu6xXdZWbXdw1+ktF6pes bp/OyYehL2Bk5TpaDzeh8TrCNQs6eIE6RDDQqf9O2Scf89DW1rPmbgjA7/ZVr/hkqUXk CmCw== X-Gm-Message-State: ACgBeo2FZyQkhj3rrexdtT0SZGSMTQdXkyiylcxGoFbCX71NY5mShxsU qZO2tBbs167uwHGkUCTIZLatcg== X-Google-Smtp-Source: AA6agR6a2tkSKcXvOkhpwgJXaxn6qr4k21/Nygc6Bo9hxI7CsKNxw/3JGemz1LbLs53jqC6gBwaMBg== X-Received: by 2002:a17:902:ccd1:b0:172:5c49:34be with SMTP id z17-20020a170902ccd100b001725c4934bemr22117194ple.23.1661888454066; Tue, 30 Aug 2022 12:40:54 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id h21-20020a17090aa89500b001fd982478cbsm6344983pjq.45.2022.08.30.12.40.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Aug 2022 12:40:53 -0700 (PDT) Date: Tue, 30 Aug 2022 19:40:49 +0000 From: Carlos Llamas To: Liam Howlett Cc: Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Suren Baghdasaryan , Andrew Morton , "kernel-team@android.com" , "syzbot+f7dc54e5be28950ac459@syzkaller.appspotmail.com" , "syzbot+a75ebe0452711c9e56d9@syzkaller.appspotmail.com" , "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/7] binder: fix alloc->vma_vm_mm null-ptr dereference Message-ID: References: <20220829201254.1814484-1-cmllamas@google.com> <20220829201254.1814484-2-cmllamas@google.com> <20220830190515.dlrp2a3ypfyhzid5@revolver> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220830190515.dlrp2a3ypfyhzid5@revolver> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Aug 30, 2022 at 07:06:37PM +0000, Liam Howlett wrote: > > diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c > > index 51f4e1c5cd01..9b1778c00610 100644 > > --- a/drivers/android/binder_alloc.c > > +++ b/drivers/android/binder_alloc.c > > @@ -322,7 +322,6 @@ static inline void binder_alloc_set_vma(struct binder_alloc *alloc, > > */ > > if (vma) { > > vm_start = vma->vm_start; > > - alloc->vma_vm_mm = vma->vm_mm; > > Is this really the null pointer dereference? We check for vma above..? > Not here. The sequence leading to the null-ptr-deref happens when we try to take alloc->vma_vm_mm->mmap_lock in binder_alloc_new_buf_locked() and in binder_alloc_print_pages() without initializing alloc->vma_vm_mm first (e.g. mmap() was never called). These sequences are described in the commit message but basically they translate to mmap_read_lock(NULL) calls.