From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by kanga.kvack.org (Postfix) with ESMTP id 3D2128E0001 for ; Sat, 29 Dec 2018 01:38:22 -0500 (EST) Received: by mail-io1-f69.google.com with SMTP id d20so20699725iom.0 for ; Fri, 28 Dec 2018 22:38:22 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id p140sor33220668itp.36.2018.12.28.22.38.21 for (Google Transport Security); Fri, 28 Dec 2018 22:38:21 -0800 (PST) MIME-Version: 1.0 References: <000000000000b57d19057e1b383d@google.com> <20181228130938.c9e42c213cdcc35a93dd0dac@linux-foundation.org> <20181228235106.okk3oastsnpxusxs@kshutemo-mobl1> In-Reply-To: <20181228235106.okk3oastsnpxusxs@kshutemo-mobl1> From: Dmitry Vyukov Date: Sat, 29 Dec 2018 07:38:08 +0100 Message-ID: Subject: Re: KASAN: use-after-free Read in filemap_fault Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Andrew Morton , syzbot , "Darrick J. Wong" , Johannes Weiner , Hugh Dickins , Jan Kara , josef@toxicpanda.com, Souptick Joarder , LKML , Linux-MM , Stephen Rothwell , syzkaller-bugs , Matthew Wilcox On Sat, Dec 29, 2018 at 12:51 AM Kirill A. Shutemov wrote: > > On Fri, Dec 28, 2018 at 01:09:38PM -0800, Andrew Morton wrote: > > On Fri, 28 Dec 2018 12:51:04 -0800 syzbot wrote: > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > uh-oh. Josef, could you please take a look? > > > > : page = find_get_page(mapping, offset); > > : if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { > > : /* > > : * We found the page, so try async readahead before > > : * waiting for the lock. > > : */ > > : fpin = do_async_mmap_readahead(vmf, page); > > : } else if (!page) { > > : /* No page in the page cache at all */ > > : fpin = do_sync_mmap_readahead(vmf); > > : count_vm_event(PGMAJFAULT); > > : count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); > > > > vmf->vma has been freed at this point. > > > > : ret = VM_FAULT_MAJOR; > > : retry_find: > > : page = pagecache_get_page(mapping, offset, > > : FGP_CREAT|FGP_FOR_MMAP, > > : vmf->gfp_mask); > > : if (!page) { > > : if (fpin) > > : goto out_retry; > > : return vmf_error(-ENOMEM); > > : } > > : } > > > > Here's a fixup for "filemap: drop the mmap_sem for all blocking operations". If you are going to squash this, please add: Tested-by: syzbot+b437b5a429d680cf2217@syzkaller.appspotmail.com > do_sync_mmap_readahead() drops mmap_sem now, so by the time of > dereferencing vmf->vma for count_memcg_event_mm() the VMA can be gone. > > diff --git a/mm/filemap.c b/mm/filemap.c > index 00a9315f45d4..65c85c47bdb1 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2554,10 +2554,10 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) > fpin = do_async_mmap_readahead(vmf, page); > } else if (!page) { > /* No page in the page cache at all */ > - fpin = do_sync_mmap_readahead(vmf); > count_vm_event(PGMAJFAULT); > count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); > ret = VM_FAULT_MAJOR; > + fpin = do_sync_mmap_readahead(vmf); > retry_find: > page = pagecache_get_page(mapping, offset, > FGP_CREAT|FGP_FOR_MMAP, > -- > Kirill A. Shutemov > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181228235106.okk3oastsnpxusxs%40kshutemo-mobl1. > For more options, visit https://groups.google.com/d/optout. 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=-11.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 769FBC43387 for ; Sat, 29 Dec 2018 06:38:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2A54720866 for ; Sat, 29 Dec 2018 06:38:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DOZNU3tn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2A54720866 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8659A8E0059; Sat, 29 Dec 2018 01:38:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7EDE08E0001; Sat, 29 Dec 2018 01:38:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 68FE08E0059; Sat, 29 Dec 2018 01:38:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by kanga.kvack.org (Postfix) with ESMTP id 3D2128E0001 for ; Sat, 29 Dec 2018 01:38:22 -0500 (EST) Received: by mail-io1-f69.google.com with SMTP id d20so20699725iom.0 for ; Fri, 28 Dec 2018 22:38:22 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=0ZeViuD5AR+Y+bp3iOoy+E0zr6PwSy4elFOzmd/xbXE=; b=Uvnfm9C6Qje8rJSahTT91xCamNP/+YAIyFqJCd7wiQZtWWuuC6TVIGueov4s8Q2QQ7 zG94JecDFf1lme/uxUbRPmIk3BsipR61S4buVNUTabFZkOXbjVlA6fEuIYSCT0Gpmjc/ BsxcWxN3xLG2U0SKIoXeKm/Df/dFtnUmfV9I4scxSwKk5tOlYzBfg4rTnGBPEFhBlOtX b72YHNp2NvsYfqYqpTceJHtcy8ujiiNiTjVCJaFTRlyCk1SUp5On+hVncJjzFu8ETbUS GvaVKbnqROfKHB+GAGB1Hx2GgkattUzIfMwoiGtamoAJcKtf+71QvCveFVtRTkUNY/tF hM4w== X-Gm-Message-State: AA+aEWbHFOkKrPgbrf5YF2L1LcEHKvNirGYX5OvsIoMZOcGvuw/E4HSt K08z2FczzKmwEKqAp9yYK8Vnxh9pkvgfLrTZ+Y5gPavr/S5I+M74IlQXyocJylaVtrQGM5ZCIJi NC96V6BUR4vuhpsJ76dnw/K9c440NyzrIsg+BYwZqg/n+I5Z/5xLWYbsDEoTSKCCtpzQmFi600C 0nyypcZ+XMTpXOIm6Qa1uPTb1DeuNf5DFJnVcAqeEPucDEKTvirbdlMoLK4kPnT5okWSOqMegzN 3kj4jlUpSJLZinf0aRThWLi1l4Pao/RePk+4/4CS+DnmfGbi8uxJARXmFugGkCVqvTc4A/ZSyCl 8O/hA+s1OTHMxfi+ei+KrgasoThF2RNqunT3BCx6ex+XF2B1aYk6UrgEZqnn2zGCqPIQn2T8vx2 M X-Received: by 2002:a24:3dca:: with SMTP id n193mr20896902itn.48.1546065501967; Fri, 28 Dec 2018 22:38:21 -0800 (PST) X-Received: by 2002:a24:3dca:: with SMTP id n193mr20896886itn.48.1546065501187; Fri, 28 Dec 2018 22:38:21 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1546065501; cv=none; d=google.com; s=arc-20160816; b=c7LihLx/5hjSM2XxlfYTPC+k+p6reg3Xu1WuibOO/Dltph7WdK5qF7tSvs8sZlFx0d /ct3IplsoCTGiAR/ukyJbeib99tBEHhGPrFAjieKjc9M0kqWST6ZTv8ovGmqPtYA1ps4 uC/rvSy3QXLAGYXhYL9cam1Hjk3egITvBSaDkwbY9CgOPDseuM0nFX+coZ/jQbZ/S+oX zZCJ8O16F4hRvOpgvDxSNzmoP5E3/urqLOxuBwDBekWF3ANL1LXN6t0gzyf5TpkIW13M URQjOFek0+W6xfWzLOVY21O616gpC2M6TO86zEVBKryGd8p+hZCUvbtXg06aYiQ4iHr3 KzGQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=0ZeViuD5AR+Y+bp3iOoy+E0zr6PwSy4elFOzmd/xbXE=; b=O9OX4ouPyhtRpBxSq5DdSULOis9FJSXLAf5lVnwS7xNhfPypQQP2q7daPALEAueHTV dWw7EHZ8oKtGvUrsHToli3qeRKSyMz8QQQ8nz8eeRxE5HeHLlRXeWS5FZgvJKymgtU7e 2Ubijjk2JIwlv0HQQicrlB9WWfbIN8zrTsys98MU0SifvhsL4LQp2msHJDtWarSE6r6w sxV8mbqsOLSIWf1lQ4IfHOPWysehCPLBOgVaaxqy0dsF3TKYO2AcO7mqUjhbdBmeroea zjZDiNyd/XAEwog4TFPLviGQAwervfrc/Y2Dfp61Bt5HAk8cK82iIcmVRO+HmEXA6vf5 cLwg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=DOZNU3tn; spf=pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dvyukov@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id p140sor33220668itp.36.2018.12.28.22.38.21 for (Google Transport Security); Fri, 28 Dec 2018 22:38:21 -0800 (PST) Received-SPF: pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=DOZNU3tn; spf=pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dvyukov@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0ZeViuD5AR+Y+bp3iOoy+E0zr6PwSy4elFOzmd/xbXE=; b=DOZNU3tnUpe3S5szXlK+1lPigHq7aVQtRCwSeOBr7gaBXGdeui6Lefv2gCbxrvhn4o RbWLUDO8qEUnJkMxq2zEAXSLxJ9/y6o38Quqt8VWYmKWtsDYidlFGwwiEw6t8OMzBTG+ S/aU4oCrIqovMK1nGSYaaGRixhV9i89JAAvKbR+1pMFyrbUCovEI8QCrUFE7VdktPkED ys5KH1faWRcfS+JZuLyl7MGHsvHjtmfquZkvtPX1Pq0h1gHNDZzmFl8eUsmeWZPon+kS 8J1zfM8LHG7bvwC6Ek8aZ1zpYi7THDHhnCU67rj8XgpCZ9szi7bfYJAQgfOJwLTKZVIm wPZA== X-Google-Smtp-Source: AFSGD/VTVfmZo7L+A3EKKs5v5i701C7j+p049SieQz8gnFKGhE1cYMuWcvH8o1w6L7mw6Z5qngDH1UXv/vP88thKM84= X-Received: by 2002:a24:b20e:: with SMTP id u14mr19830088ite.12.1546065500564; Fri, 28 Dec 2018 22:38:20 -0800 (PST) MIME-Version: 1.0 References: <000000000000b57d19057e1b383d@google.com> <20181228130938.c9e42c213cdcc35a93dd0dac@linux-foundation.org> <20181228235106.okk3oastsnpxusxs@kshutemo-mobl1> In-Reply-To: <20181228235106.okk3oastsnpxusxs@kshutemo-mobl1> From: Dmitry Vyukov Date: Sat, 29 Dec 2018 07:38:08 +0100 Message-ID: Subject: Re: KASAN: use-after-free Read in filemap_fault To: "Kirill A. Shutemov" Cc: Andrew Morton , syzbot , "Darrick J. Wong" , Johannes Weiner , Hugh Dickins , Jan Kara , josef@toxicpanda.com, Souptick Joarder , LKML , Linux-MM , Stephen Rothwell , syzkaller-bugs , Matthew Wilcox Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20181229063808.pSdyjRPwDaOwyPSO5Z7Xob0SwoqeBDGO7YW1g4Oc0eg@z> On Sat, Dec 29, 2018 at 12:51 AM Kirill A. Shutemov wrote: > > On Fri, Dec 28, 2018 at 01:09:38PM -0800, Andrew Morton wrote: > > On Fri, 28 Dec 2018 12:51:04 -0800 syzbot wrote: > > > > > Hello, > > > > > > syzbot found the following crash on: > > > > uh-oh. Josef, could you please take a look? > > > > : page = find_get_page(mapping, offset); > > : if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { > > : /* > > : * We found the page, so try async readahead before > > : * waiting for the lock. > > : */ > > : fpin = do_async_mmap_readahead(vmf, page); > > : } else if (!page) { > > : /* No page in the page cache at all */ > > : fpin = do_sync_mmap_readahead(vmf); > > : count_vm_event(PGMAJFAULT); > > : count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); > > > > vmf->vma has been freed at this point. > > > > : ret = VM_FAULT_MAJOR; > > : retry_find: > > : page = pagecache_get_page(mapping, offset, > > : FGP_CREAT|FGP_FOR_MMAP, > > : vmf->gfp_mask); > > : if (!page) { > > : if (fpin) > > : goto out_retry; > > : return vmf_error(-ENOMEM); > > : } > > : } > > > > Here's a fixup for "filemap: drop the mmap_sem for all blocking operations". If you are going to squash this, please add: Tested-by: syzbot+b437b5a429d680cf2217@syzkaller.appspotmail.com > do_sync_mmap_readahead() drops mmap_sem now, so by the time of > dereferencing vmf->vma for count_memcg_event_mm() the VMA can be gone. > > diff --git a/mm/filemap.c b/mm/filemap.c > index 00a9315f45d4..65c85c47bdb1 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2554,10 +2554,10 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) > fpin = do_async_mmap_readahead(vmf, page); > } else if (!page) { > /* No page in the page cache at all */ > - fpin = do_sync_mmap_readahead(vmf); > count_vm_event(PGMAJFAULT); > count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT); > ret = VM_FAULT_MAJOR; > + fpin = do_sync_mmap_readahead(vmf); > retry_find: > page = pagecache_get_page(mapping, offset, > FGP_CREAT|FGP_FOR_MMAP, > -- > Kirill A. Shutemov > > -- > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/20181228235106.okk3oastsnpxusxs%40kshutemo-mobl1. > For more options, visit https://groups.google.com/d/optout.