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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 0D736C43387 for ; Mon, 17 Dec 2018 15:58:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1588206A2 for ; Mon, 17 Dec 2018 15:58:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388028AbeLQP6i (ORCPT ); Mon, 17 Dec 2018 10:58:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50918 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726667AbeLQP6h (ORCPT ); Mon, 17 Dec 2018 10:58:37 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8DB38D7936; Mon, 17 Dec 2018 15:58:37 +0000 (UTC) Received: from [10.36.112.24] (ovpn-112-24.ams2.redhat.com [10.36.112.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BE6365D744; Mon, 17 Dec 2018 15:58:33 +0000 (UTC) Subject: Re: KASAN: use-after-free Read in kvm_put_kvm (caused by: "kvm/x86: add coalesced pio support") To: Eric Biggers , Peng Hao Cc: syzbot , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, rkrcmar@redhat.com, syzkaller-bugs@googlegroups.com References: <000000000000bc23740578abe82c@google.com> <3ad5acd8-5c73-1d82-aea5-426e598b15ed@redhat.com> <20181216185513.GA691@sol.localdomain> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; keydata= mQHhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAbQj UGFvbG8gQm9uemluaSA8cGJvbnppbmlAcmVkaGF0LmNvbT6JAg0EEwECACMFAlRCcBICGwMH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRB+FRAMzTZpsbceDp9IIN6BIA0Ol7MoB15E 11kRz/ewzryFY54tQlMnd4xxfH8MTQ/mm9I482YoSwPMdcWFAKnUX6Yo30tbLiNB8hzaHeRj jx12K+ptqYbg+cevgOtbLAlL9kNgLLcsGqC2829jBCUTVeMSZDrzS97ole/YEez2qFpPnTV0 VrRWClWVfYh+JfzpXmgyhbkuwUxNFk421s4Ajp3d8nPPFUGgBG5HOxzkAm7xb1cjAuJ+oi/K CHfkuN+fLZl/u3E/fw7vvOESApLU5o0icVXeakfSz0LsygEnekDbxPnE5af/9FEkXJD5EoYG SEahaEtgNrR4qsyxyAGYgZlS70vkSSYJ+iT2rrwEiDlo31MzRo6Ba2FfHBSJ7lcYdPT7bbk9 AO3hlNMhNdUhoQv7M5HsnqZ6unvSHOKmReNaS9egAGdRN0/GPDWr9wroyJ65ZNQsHl9nXBqE AukZNr5oJO5vxrYiAuuTSd6UI/xFkjtkzltG3mw5ao2bBpk/V/YuePrJsnPFHG7NhizrxttB nTuOSCMo45pfHQ+XYd5K1+Cv/NzZFNWscm5htJ0HznY+oOsZvHTyGz3v91pn51dkRYN0otqr bQ4tlFFuVjArBZcapSIe6NV8C4cEiSS5AQ0EVEJxcwEIAK+nUrsUz3aP2aBjIrX3a1+C+39R nctpNIPcJjFJ/8WafRiwcEuLjbvJ/4kyM6K7pWUIQftl1P8Woxwb5nqL7zEFHh5I+hKS3haO 5pgco//V0tWBGMKinjqntpd4U4Dl299dMBZ4rRbPvmI8rr63sCENxTnHhTECyHdGFpqSzWzy 97rH68uqMpxbUeggVwYkYihZNd8xt1+lf7GWYNEO/QV8ar/qbRPG6PEfiPPHQd/sldGYavmd //o6TQLSJsvJyJDt7KxulnNT8Q2X/OdEuVQsRT5glLaSAeVAABcLAEnNgmCIGkX7TnQF8a6w gHGrZIR9ZCoKvDxAr7RP6mPeS9sAEQEAAYkDEgQYAQIACQUCVEJxcwIbAgEpCRB+FRAMzTZp scBdIAQZAQIABgUCVEJxcwAKCRC/+9JfeMeug/SlCACl7QjRnwHo/VzENWD9G2VpUOd9eRnS DZGQmPo6Mp3Wy8vL7snGFBfRseT9BevXBSkxvtOnUUV2YbyLmolAODqUGzUI8ViF339poOYN i6Ffek0E19IMQ5+CilqJJ2d5ZvRfaq70LA/Ly9jmIwwX4auvXrWl99/2wCkqnWZI+PAepkcX JRD4KY2fsvRi64/aoQmcxTiyyR7q3/52Sqd4EdMfj0niYJV0Xb9nt8G57Dp9v3Ox5JeWZKXS krFqy1qyEIypIrqcMbtXM7LSmiQ8aJRM4ZHYbvgjChJKR4PsKNQZQlMWGUJO4nVFSkrixc9R Z49uIqQK3b3ENB1QkcdMg9cxsB0Onih8zR+Wp1uDZXnz1ekto+EivLQLqvTjCCwLxxJafwKI bqhQ+hGR9jF34EFur5eWt9jJGloEPVv0GgQflQaE+rRGe+3f5ZDgRe5Y/EJVNhBhKcafcbP8 MzmLRh3UDnYDwaeguYmxuSlMdjFL96YfhRBXs8tUw6SO9jtCgBvoOIBDCxxAJjShY4KIvEpK b2hSNr8KxzelKKlSXMtB1bbHbQxiQcerAipYiChUHq1raFc3V0eOyCXK205rLtknJHhM5pfG 6taABGAMvJgm/MrVILIxvBuERj1FRgcgoXtiBmLEJSb7akcrRlqe3MoPTntSTNvNzAJmfWhd SvP0G1WDLolqvX0OtKMppI91AWVu72f1kolJg43wbaKpRJg1GMkKEI3H+jrrlTBrNl/8e20m TElPRDKzPiowmXeZqFSS1A6Azv0TJoo9as+lWF+P4zCXt40+Zhh5hdHO38EV7vFAVG3iuay6 7ToF8Uy7tgc3mdH98WQSmHcn/H5PFYk3xTP3KHB7b0FZPdFPQXBZb9+tJeZBi9gMqcjMch+Y R8dmTcQRQX14bm5nXlBF7VpSOPZMR392LY7wzAvRdhz7aeIUkdO7VelaspFk2nT7wOj1Y6uL nRxQlLkBDQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAemVv9Yfn2PbDIbxXqLff7o yVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CRwkMHtOmzQiQ2tSLjKh/c HeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuffAb589AJW50kkQK9VD/9 QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v028TVAaYbIhxvDY0hUQE4r 8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQzCYHXAzwnGi8WU9iuE1P 0wARAQABiQHzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EOoJy0uZggJm7gZKeJ7iUp eX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBTuiJ0bfo55SWsUNN+c9hh IX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHnplOzCXHvmdlW0i6SrMsB Dl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4HYv/7ZnASVkR5EERFF3+ 6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz876SvcOb5SL5SKg9/rCB ufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvriy9enJ8kxJwhC0ECbSKF Y+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y1lJAPPSIqZKvHzGShdh8 DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT/ujKaGd4vxG2Ei+MMNDm S1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO53DliFMkVTecLptsXaes uUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: <5b22a63b-e4c2-58af-8070-5aec20302dfc@redhat.com> Date: Mon, 17 Dec 2018 16:58:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <20181216185513.GA691@sol.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Mon, 17 Dec 2018 15:58:37 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/12/18 19:55, Eric Biggers wrote: > Hi Peng and Paolo, > > On Sun, Oct 21, 2018 at 12:01:55PM +0200, Paolo Bonzini wrote: >> On 20/10/2018 18:57, syzbot wrote: >>> Hello, >>> >>> syzbot found the following crash on: >>> >>> HEAD commit:    8c60c36d0b8c Add linux-next specific files for 20181019 >>> git tree:       linux-next >>> console output: https://syzkaller.appspot.com/x/log.txt?x=12d808b5400000 >>> kernel config:  https://syzkaller.appspot.com/x/.config?x=8b6d7c4c81535e89 >>> dashboard link: >>> https://syzkaller.appspot.com/bug?extid=f87f60bb6f13f39b54e3 >>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental) >>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17cf2f5e400000 >>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1036dcce400000 >>> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: >>> Reported-by: syzbot+f87f60bb6f13f39b54e3@syzkaller.appspotmail.com >> >> Tentative (untested) patch: >> >> diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c >> index 3710342cf6ad..dc76cc8d24fd 100644 >> --- a/virt/kvm/coalesced_mmio.c >> +++ b/virt/kvm/coalesced_mmio.c >> @@ -90,6 +90,7 @@ static int coalesced_mmio_write(struct kvm_vcpu *vcpu, >> return 0; >> } >> >> +/* called with kvm->slots_lock held */ >> static void coalesced_mmio_destructor(struct kvm_io_device *this) >> { >> struct kvm_coalesced_mmio_dev *dev = to_mmio(this); >> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c >> index b20b751286fc..001e1ef18c8c 100644 >> --- a/virt/kvm/eventfd.c >> +++ b/virt/kvm/eventfd.c >> @@ -741,8 +741,8 @@ ioeventfd_write(struct kvm_vcpu *vcpu, struct >> kvm_io_device *this, gpa_t addr, >> } >> >> /* >> - * This function is called as KVM is completely shutting down. We do not >> - * need to worry about locking just nuke anything we have as quickly as >> possible >> + * This function is called as KVM is completely shutting down, so there >> + * are no RCU readers anymore. Called with kvm->slots_lock held. >> */ >> static void >> ioeventfd_destructor(struct kvm_io_device *this) >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index aff1242b7af7..e6f2ae6fedcd 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -783,6 +783,7 @@ static void kvm_destroy_vm(struct kvm *kvm) >> list_del(&kvm->vm_list); >> spin_unlock(&kvm_lock); >> kvm_free_irq_routing(kvm); >> + mutex_lock(&kvm->slots_lock); >> for (i = 0; i < KVM_NR_BUSES; i++) { >> struct kvm_io_bus *bus = kvm_get_bus(kvm, i); >> >> @@ -790,6 +791,7 @@ static void kvm_destroy_vm(struct kvm *kvm) >> kvm_io_bus_destroy(bus); >> kvm->buses[i] = NULL; >> } >> + mutex_unlock(&kvm->slots_lock); >> kvm_coalesced_mmio_free(kvm); >> #ifdef KVM_DIRTY_LOG_PAGE_OFFSET >> if (kvm->dirty_ring_size) >> > > This is still happening. Paolo, I don't see how your patch matches this bug, as > it has a single threaded reproducer. I simplified it to: > > #include > #include > #include > > int main(void) > { > int kvm, vm; > struct kvm_coalesced_mmio_zone zone = { 0 }; > > kvm = open("/dev/kvm", O_RDWR); > > vm = ioctl(kvm, KVM_CREATE_VM, 0); > > ioctl(vm, KVM_REGISTER_COALESCED_MMIO, &zone); > > zone.pio = 1; > ioctl(vm, KVM_UNREGISTER_COALESCED_MMIO, &zone); > } > > The bug is in this commit: > > commit 0804c849f1df0992d39a37c4fc259f7f8b16f385 > Author: Peng Hao > Date: Sun Oct 14 07:09:55 2018 +0800 > > kvm/x86 : add coalesced pio support > > The problem is that if you register a kvm_coalesced_mmio_zone with '.pio = 0' > but then unregister it with '.pio = 1', KVM_UNREGISTER_COALESCED_MMIO will try > to unregister it from KVM_PIO_BUS rather than KVM_MMIO_BUS, which is a no-op, > but then it frees the kvm_coalesced_mmio_dev anyway. > > Here's one possible fix but I don't know what was intended here. Are you > supposed to pass in the same value of '.pio' when unregistering or is it > supposed to use the existing value? Can one of you please point me to the > documentation for these ioctls? > > diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c > index 3710342cf6ad0..6855cce3e5287 100644 > --- a/virt/kvm/coalesced_mmio.c > +++ b/virt/kvm/coalesced_mmio.c > @@ -175,10 +175,14 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, > { > struct kvm_coalesced_mmio_dev *dev, *tmp; > > + if (zone->pio != 1 && zone->pio != 0) > + return -EINVAL; > + > mutex_lock(&kvm->slots_lock); > > list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list) > - if (coalesced_mmio_in_range(dev, zone->addr, zone->size)) { > + if (zone->pio == dev->zone.pio && > + coalesced_mmio_in_range(dev, zone->addr, zone->size)) { > kvm_io_bus_unregister_dev(kvm, > zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev); > kvm_iodevice_destructor(&dev->dev); > Yes, this is the fix. The same range can be registered both with .pio = 0 and .pio = 1. Paolo