From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752885AbdDKPlj (ORCPT ); Tue, 11 Apr 2017 11:41:39 -0400 Received: from mail-pf0-f172.google.com ([209.85.192.172]:32795 "EHLO mail-pf0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752689AbdDKPlh (ORCPT ); Tue, 11 Apr 2017 11:41:37 -0400 MIME-Version: 1.0 In-Reply-To: References:

<3a57c408-8aa5-d339-4176-add4924e817d@arm.com> <0fc0380f-f108-7d20-ee8a-1b044fa1f115@arm.com> <2200dd06-2374-b95d-131b-5a2437d14007@arm.com> <7f9de429-d9e5-eb89-c72e-e002a65e8e0f@arm.com>

From: Andrey Konovalov Date: Tue, 11 Apr 2017 17:41:35 +0200 Message-ID: Subject: Re: kvm/arm64: use-after-free in kvm_vm_ioctl/vmacache_update To: Marc Zyngier Cc: Suzuki K Poulose , Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Christoffer Dall , Catalin Marinas , Will Deacon , Ingo Molnar , Michal Hocko , Christian Borntraeger , Suraj Jitindar Singh , Markus Elfring , Lorenzo Stoakes , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, LKML , Dmitry Vyukov , Kostya Serebryany , syzkaller Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 11, 2017 at 5:36 PM, Marc Zyngier wrote: > On 11/04/17 16:26, Andrey Konovalov wrote: >> On Tue, Mar 14, 2017 at 1:26 PM, Marc Zyngier wrote: >>> On 14/03/17 11:03, Suzuki K Poulose wrote: >>>> On 13/03/17 09:58, Marc Zyngier wrote: >>>>> On 10/03/17 18:37, Suzuki K Poulose wrote: >>>>>> On 10/03/17 15:50, Andrey Konovalov wrote: >>>>>>> On Fri, Mar 10, 2017 at 2:38 PM, Andrey Konovalov wrote: >>>>>>>> Hi, >>>>>>>> >>>>>>>> I've got the following error report while fuzzing the kernel with syzkaller. >>>>>>>> >>>>>>>> On linux-next commit 56b8bad5e066c23e8fa273ef5fba50bd3da2ace8 (Mar 8). >>>>>>>> >>>>>>>> Unfortunately I can't reproduce it. >>>>>>>> >>>>>>>> ================================================================== >>>>>>>> BUG: KASAN: use-after-free in vmacache_update+0x114/0x118 mm/vmacache.c:63 >>>>>>>> Read of size 8 at addr ffff80003b9a2040 by task syz-executor/26615 >>>>>>>> >>>>>>>> CPU: 1 PID: 26615 Comm: syz-executor Not tainted >>>>>>>> 4.11.0-rc1-next-20170308-xc2-dirty #3 >>>>>>>> Hardware name: Hardkernel ODROID-C2 (DT) >>>>>>>> Call trace: >>>>>>>> [] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:505 >>>>>>>> [] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:228 >>>>>>>> [] __dump_stack lib/dump_stack.c:16 [inline] >>>>>>>> [] dump_stack+0x110/0x168 lib/dump_stack.c:52 >>>>>>>> [] print_address_description+0x60/0x248 mm/kasan/report.c:250 >>>>>>>> [] kasan_report_error+0xe8/0x250 mm/kasan/report.c:349 >>>>>>>> [] kasan_report mm/kasan/report.c:372 [inline] >>>>>>>> [] __asan_report_load8_noabort+0x3c/0x48 mm/kasan/report.c:393 >>>>>>>> [] vmacache_update+0x114/0x118 mm/vmacache.c:63 >>>>>>>> [] find_vma+0xf8/0x150 mm/mmap.c:2124 >>>>>>>> [] kvm_arch_prepare_memory_region+0x2ac/0x488 >>>>>>>> arch/arm64/kvm/../../../arch/arm/kvm/mmu.c:1817 >>>>>>>> [] __kvm_set_memory_region+0x3d8/0x12b8 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1026 >>>>>>>> [] kvm_set_memory_region+0x38/0x58 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1075 >>>>>>>> [] kvm_vm_ioctl_set_memory_region >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1087 [inline] >>>>>>>> [] kvm_vm_ioctl+0xb94/0x1308 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:2960 >>>>>>>> [] vfs_ioctl fs/ioctl.c:45 [inline] >>>>>>>> [] do_vfs_ioctl+0x128/0xfc0 fs/ioctl.c:685 >>>>>>>> [] SYSC_ioctl fs/ioctl.c:700 [inline] >>>>>>>> [] SyS_ioctl+0xa8/0xb8 fs/ioctl.c:691 >>>>>>>> [] el0_svc_naked+0x24/0x28 >>>>>>>> >>>>>>>> Allocated by task 26657: >>>>>>>> save_stack_trace_tsk+0x0/0x330 arch/arm64/kernel/stacktrace.c:133 >>>>>>>> save_stack_trace+0x20/0x30 arch/arm64/kernel/stacktrace.c:216 >>>>>>>> save_stack mm/kasan/kasan.c:515 [inline] >>>>>>>> set_track mm/kasan/kasan.c:527 [inline] >>>>>>>> kasan_kmalloc+0xd4/0x180 mm/kasan/kasan.c:619 >>>>>>>> kasan_slab_alloc+0x14/0x20 mm/kasan/kasan.c:557 >>>>>>>> slab_post_alloc_hook mm/slab.h:456 [inline] >>>>>>>> slab_alloc_node mm/slub.c:2718 [inline] >>>>>>>> slab_alloc mm/slub.c:2726 [inline] >>>>>>>> kmem_cache_alloc+0x144/0x230 mm/slub.c:2731 >>>>>>>> __split_vma+0x118/0x608 mm/mmap.c:2515 >>>>>>>> do_munmap+0x194/0x9b0 mm/mmap.c:2636 >>>>>>>> Freed by task 26657: >>>>>>>> save_stack_trace_tsk+0x0/0x330 arch/arm64/kernel/stacktrace.c:133 >>>>>>>> save_stack_trace+0x20/0x30 arch/arm64/kernel/stacktrace.c:216 >>>>>>>> save_stack mm/kasan/kasan.c:515 [inline] >>>>>>>> set_track mm/kasan/kasan.c:527 [inline] >>>>>>>> kasan_slab_free+0x84/0x198 mm/kasan/kasan.c:592 >>>>>>>> slab_free_hook mm/slub.c:1357 [inline] >>>>>>>> slab_free_freelist_hook mm/slub.c:1379 [inline] >>>>>>>> slab_free mm/slub.c:2961 [inline] >>>>>>>> kmem_cache_free+0x80/0x258 mm/slub.c:2983 >>>>>>>> __vma_adjust+0x6b0/0xf mm/mmap.c:890] el0_svc_naked+0x24/0x28 >>>>>>>> >>>>>>>> The buggy address belongs to the object at ffff80003b9a2000 >>>>>>>> which belongs to the cache vm_area_struct(647:session-6.scope) of size 184 >>>>>>>> The buggy address is located 64 bytes inside of >>>>>>>> 184-byte region [ffff80003b9a2000, ffff80003b9a20b8) >>>>>>>> The buggy address belongs to the page: >>>>>>>> page:ffff7e0000ee6880 count:1 mapcount:0 mapping: (null) index:0x0 >>>>>>>> flags: 0xfffc00000000100(slab) >>>>>>>> raw: 0fffc00000000100 0000000000000000 0000000000000000 0000000180100010 >>>>>>>> raw: 0000000000000000 0000000c00000001 ffff80005a5cc600 ffff80005ac99980 >>>>>>>> page dumped because: kasan: bad access detected >>>>>>>> page->mem_cgroup:ffff80005ac99980 >>>>>>>> >>>>>>>> Memory state around the buggy address: >>>>>>>> ffff80003b9a1f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>>>>> ffff80003b9a1f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>>>>>> ffff80003b9a2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>>>>>> ^ >>>>>>>> ffff80003b9a2080: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fb >>>>>>>> ffff80003b9a2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>>>>>> ================================================================== >>>>>>> >>>>>>> Another one that looks related and doesn't have parts of stack traces missing: >>>>>>> >>>>>>> ================================================================== >>>>>>> BUG: KASAN: use-after-free in find_vma+0x140/0x150 mm/mmap.c:2114 >>>>>>> Read of size 8 at addr ffff800031a03e90 by task syz-executor/4360 >>>>>>> >>>>>>> CPU: 2 PID: 4360 Comm: syz-executor Not tainted >>>>>>> 4.11.0-rc1-next-20170308-xc2-dirty #3 >>>>>>> Hardware name: Hardkernel ODROID-C2 (DT) >>>>>>> Call trace: >>>>>>> [] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:505 >>>>>>> [] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:228 >>>>>>> [] __dump_stack lib/dump_stack.c:16 [inline] >>>>>>> [] dump_stack+0x110/0x168 lib/dump_stack.c:52 >>>>>>> [] print_address_description+0x60/0x248 mm/kasan/report.c:250 >>>>>>> [] kasan_report_error+0xe8/0x250 mm/kasan/report.c:349 >>>>>>> [] kasan_report mm/kasan/report.c:372 [inline] >>>>>>> [] __asan_report_load8_noabort+0x3c/0x48 mm/kasan/report.c:393 >>>>>>> [] find_vma+0x140/0x150 mm/mmap.c:2114 >>>>>>> [] kvm_arch_prepare_memory_region+0x2ac/0x488 >>>>>>> arch/arm64/kvm/../../../arch/arm/kvm/mmu.c:1817 >>>>>> >>>>>> It looks like we don't take the mmap_sem before calling find_vma() in >>>>>> stage2_unmap_memslot() and in kvm_arch_prepare_memory_region(), which is causing >>>>>> the race, with probably the test trying to unmap ranges in between. >>>>> >>>>> That indeed seems like a possible failure mode. The annoying thing is >>>>> that we're not exactly in a position to take mmap_sem in >>>>> stage2_unmap_memslot, since we hold the kvm->mmu_lock spinlock. We may >>>>> have to hold mmap_sem while iterating over all the memslots. >>>>> >>>>> How about the following (very lightly tested): >>>>> >>>>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c >>>>> index 962616fd4ddd..2006a79d5912 100644 >>>>> --- a/arch/arm/kvm/mmu.c >>>>> +++ b/arch/arm/kvm/mmu.c >>>>> @@ -803,6 +803,7 @@ void stage2_unmap_vm(struct kvm *kvm) >>>>> int idx; >>>>> >>>>> idx = srcu_read_lock(&kvm->srcu); >>>>> + down_read(¤t->mm->mmap_sem); >>>>> spin_lock(&kvm->mmu_lock); >>>>> >>>>> slots = kvm_memslots(kvm); >>>>> @@ -810,6 +811,7 @@ void stage2_unmap_vm(struct kvm *kvm) >>>>> stage2_unmap_memslot(kvm, memslot); >>>>> >>>>> spin_unlock(&kvm->mmu_lock); >>>>> + up_read(¤t->mm->mmap_sem); >>>>> srcu_read_unlock(&kvm->srcu, idx); >>>>> } >>>>> >>>>> @@ -1813,6 +1815,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >>>>> * | memory region | >>>>> * +--------------------------------------------+ >>>>> */ >>>>> + down_read(¤t->mm->mmap_sem); >>>>> do { >>>>> struct vm_area_struct *vma = find_vma(current->mm, hva); >>>>> hva_t vm_start, vm_end; >>>> >>>> I have added the following hunk : >>>> >>>> @@ -1844,8 +1847,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >>>> pa += vm_start - vma->vm_start; >>>> >>>> /* IO region dirty page logging not allowed */ >>>> - if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) >>>> - return -EINVAL; >>>> + if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) { >>>> + ret = -EINVAL; >>>> + goto out; >>>> + } >>>> >>>> ret = kvm_phys_addr_ioremap(kvm, gpa, pa, >>>> vm_end - vm_start, >>>> >>> >>> Ah, of course... Thanks for pointing that out, I'll fix it as I post a >>> proper patch. >>> >>> Thanks, >>> >>> M. >>> -- >>> Jazz is not dead. It just smells funny... >> >> Hi, >> >> I've got this report again on linux-next 4c3c5cd02318 (Apr 5). >> >> It seems that it's still not fixed. >> >> Thanks! >> >> ================================================================== >> BUG: KASAN: use-after-free in vmacache_update+0x114/0x118 mm/vmacache.c:63 >> Read of size 8 at addr ffff80004d53aae8 by task syz-executor/23095 >> >> CPU: 0 PID: 23095 Comm: syz-executor Not tainted >> 4.11.0-rc5-next-20170405-xc2-09030-g4c3c5cd02318-dirty #4 > > The fixes went into -rc6. Can you please give it a go? Ah, OK, I assumed they were in the linux-next revision I used. Thanks! > > Thanks, > > M. > -- > Jazz is not dead. It just smells funny... > > -- > You received this message because you are subscribed to the Google Groups "syzkaller" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrey Konovalov Subject: Re: kvm/arm64: use-after-free in kvm_vm_ioctl/vmacache_update Date: Tue, 11 Apr 2017 17:41:35 +0200 Message-ID: References:

<3a57c408-8aa5-d339-4176-add4924e817d@arm.com> <0fc0380f-f108-7d20-ee8a-1b044fa1f115@arm.com> <2200dd06-2374-b95d-131b-5a2437d14007@arm.com> <7f9de429-d9e5-eb89-c72e-e002a65e8e0f@arm.com>

Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Kostya Serebryany , Michal Hocko , Lorenzo Stoakes , kvm@vger.kernel.org, Catalin Marinas , Will Deacon , LKML , Markus Elfring , Christian Borntraeger , syzkaller , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Suraj Jitindar Singh , Dmitry Vyukov , Paolo Bonzini , Ingo Molnar To: Marc Zyngier Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On Tue, Apr 11, 2017 at 5:36 PM, Marc Zyngier wrote: > On 11/04/17 16:26, Andrey Konovalov wrote: >> On Tue, Mar 14, 2017 at 1:26 PM, Marc Zyngier wrote: >>> On 14/03/17 11:03, Suzuki K Poulose wrote: >>>> On 13/03/17 09:58, Marc Zyngier wrote: >>>>> On 10/03/17 18:37, Suzuki K Poulose wrote: >>>>>> On 10/03/17 15:50, Andrey Konovalov wrote: >>>>>>> On Fri, Mar 10, 2017 at 2:38 PM, Andrey Konovalov wrote: >>>>>>>> Hi, >>>>>>>> >>>>>>>> I've got the following error report while fuzzing the kernel with syzkaller. >>>>>>>> >>>>>>>> On linux-next commit 56b8bad5e066c23e8fa273ef5fba50bd3da2ace8 (Mar 8). >>>>>>>> >>>>>>>> Unfortunately I can't reproduce it. >>>>>>>> >>>>>>>> ================================================================== >>>>>>>> BUG: KASAN: use-after-free in vmacache_update+0x114/0x118 mm/vmacache.c:63 >>>>>>>> Read of size 8 at addr ffff80003b9a2040 by task syz-executor/26615 >>>>>>>> >>>>>>>> CPU: 1 PID: 26615 Comm: syz-executor Not tainted >>>>>>>> 4.11.0-rc1-next-20170308-xc2-dirty #3 >>>>>>>> Hardware name: Hardkernel ODROID-C2 (DT) >>>>>>>> Call trace: >>>>>>>> [] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:505 >>>>>>>> [] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:228 >>>>>>>> [] __dump_stack lib/dump_stack.c:16 [inline] >>>>>>>> [] dump_stack+0x110/0x168 lib/dump_stack.c:52 >>>>>>>> [] print_address_description+0x60/0x248 mm/kasan/report.c:250 >>>>>>>> [] kasan_report_error+0xe8/0x250 mm/kasan/report.c:349 >>>>>>>> [] kasan_report mm/kasan/report.c:372 [inline] >>>>>>>> [] __asan_report_load8_noabort+0x3c/0x48 mm/kasan/report.c:393 >>>>>>>> [] vmacache_update+0x114/0x118 mm/vmacache.c:63 >>>>>>>> [] find_vma+0xf8/0x150 mm/mmap.c:2124 >>>>>>>> [] kvm_arch_prepare_memory_region+0x2ac/0x488 >>>>>>>> arch/arm64/kvm/../../../arch/arm/kvm/mmu.c:1817 >>>>>>>> [] __kvm_set_memory_region+0x3d8/0x12b8 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1026 >>>>>>>> [] kvm_set_memory_region+0x38/0x58 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1075 >>>>>>>> [] kvm_vm_ioctl_set_memory_region >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1087 [inline] >>>>>>>> [] kvm_vm_ioctl+0xb94/0x1308 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:2960 >>>>>>>> [] vfs_ioctl fs/ioctl.c:45 [inline] >>>>>>>> [] do_vfs_ioctl+0x128/0xfc0 fs/ioctl.c:685 >>>>>>>> [] SYSC_ioctl fs/ioctl.c:700 [inline] >>>>>>>> [] SyS_ioctl+0xa8/0xb8 fs/ioctl.c:691 >>>>>>>> [] el0_svc_naked+0x24/0x28 >>>>>>>> >>>>>>>> Allocated by task 26657: >>>>>>>> save_stack_trace_tsk+0x0/0x330 arch/arm64/kernel/stacktrace.c:133 >>>>>>>> save_stack_trace+0x20/0x30 arch/arm64/kernel/stacktrace.c:216 >>>>>>>> save_stack mm/kasan/kasan.c:515 [inline] >>>>>>>> set_track mm/kasan/kasan.c:527 [inline] >>>>>>>> kasan_kmalloc+0xd4/0x180 mm/kasan/kasan.c:619 >>>>>>>> kasan_slab_alloc+0x14/0x20 mm/kasan/kasan.c:557 >>>>>>>> slab_post_alloc_hook mm/slab.h:456 [inline] >>>>>>>> slab_alloc_node mm/slub.c:2718 [inline] >>>>>>>> slab_alloc mm/slub.c:2726 [inline] >>>>>>>> kmem_cache_alloc+0x144/0x230 mm/slub.c:2731 >>>>>>>> __split_vma+0x118/0x608 mm/mmap.c:2515 >>>>>>>> do_munmap+0x194/0x9b0 mm/mmap.c:2636 >>>>>>>> Freed by task 26657: >>>>>>>> save_stack_trace_tsk+0x0/0x330 arch/arm64/kernel/stacktrace.c:133 >>>>>>>> save_stack_trace+0x20/0x30 arch/arm64/kernel/stacktrace.c:216 >>>>>>>> save_stack mm/kasan/kasan.c:515 [inline] >>>>>>>> set_track mm/kasan/kasan.c:527 [inline] >>>>>>>> kasan_slab_free+0x84/0x198 mm/kasan/kasan.c:592 >>>>>>>> slab_free_hook mm/slub.c:1357 [inline] >>>>>>>> slab_free_freelist_hook mm/slub.c:1379 [inline] >>>>>>>> slab_free mm/slub.c:2961 [inline] >>>>>>>> kmem_cache_free+0x80/0x258 mm/slub.c:2983 >>>>>>>> __vma_adjust+0x6b0/0xf mm/mmap.c:890] el0_svc_naked+0x24/0x28 >>>>>>>> >>>>>>>> The buggy address belongs to the object at ffff80003b9a2000 >>>>>>>> which belongs to the cache vm_area_struct(647:session-6.scope) of size 184 >>>>>>>> The buggy address is located 64 bytes inside of >>>>>>>> 184-byte region [ffff80003b9a2000, ffff80003b9a20b8) >>>>>>>> The buggy address belongs to the page: >>>>>>>> page:ffff7e0000ee6880 count:1 mapcount:0 mapping: (null) index:0x0 >>>>>>>> flags: 0xfffc00000000100(slab) >>>>>>>> raw: 0fffc00000000100 0000000000000000 0000000000000000 0000000180100010 >>>>>>>> raw: 0000000000000000 0000000c00000001 ffff80005a5cc600 ffff80005ac99980 >>>>>>>> page dumped because: kasan: bad access detected >>>>>>>> page->mem_cgroup:ffff80005ac99980 >>>>>>>> >>>>>>>> Memory state around the buggy address: >>>>>>>> ffff80003b9a1f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>>>>> ffff80003b9a1f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>>>>>> ffff80003b9a2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>>>>>> ^ >>>>>>>> ffff80003b9a2080: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fb >>>>>>>> ffff80003b9a2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>>>>>> ================================================================== >>>>>>> >>>>>>> Another one that looks related and doesn't have parts of stack traces missing: >>>>>>> >>>>>>> ================================================================== >>>>>>> BUG: KASAN: use-after-free in find_vma+0x140/0x150 mm/mmap.c:2114 >>>>>>> Read of size 8 at addr ffff800031a03e90 by task syz-executor/4360 >>>>>>> >>>>>>> CPU: 2 PID: 4360 Comm: syz-executor Not tainted >>>>>>> 4.11.0-rc1-next-20170308-xc2-dirty #3 >>>>>>> Hardware name: Hardkernel ODROID-C2 (DT) >>>>>>> Call trace: >>>>>>> [] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:505 >>>>>>> [] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:228 >>>>>>> [] __dump_stack lib/dump_stack.c:16 [inline] >>>>>>> [] dump_stack+0x110/0x168 lib/dump_stack.c:52 >>>>>>> [] print_address_description+0x60/0x248 mm/kasan/report.c:250 >>>>>>> [] kasan_report_error+0xe8/0x250 mm/kasan/report.c:349 >>>>>>> [] kasan_report mm/kasan/report.c:372 [inline] >>>>>>> [] __asan_report_load8_noabort+0x3c/0x48 mm/kasan/report.c:393 >>>>>>> [] find_vma+0x140/0x150 mm/mmap.c:2114 >>>>>>> [] kvm_arch_prepare_memory_region+0x2ac/0x488 >>>>>>> arch/arm64/kvm/../../../arch/arm/kvm/mmu.c:1817 >>>>>> >>>>>> It looks like we don't take the mmap_sem before calling find_vma() in >>>>>> stage2_unmap_memslot() and in kvm_arch_prepare_memory_region(), which is causing >>>>>> the race, with probably the test trying to unmap ranges in between. >>>>> >>>>> That indeed seems like a possible failure mode. The annoying thing is >>>>> that we're not exactly in a position to take mmap_sem in >>>>> stage2_unmap_memslot, since we hold the kvm->mmu_lock spinlock. We may >>>>> have to hold mmap_sem while iterating over all the memslots. >>>>> >>>>> How about the following (very lightly tested): >>>>> >>>>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c >>>>> index 962616fd4ddd..2006a79d5912 100644 >>>>> --- a/arch/arm/kvm/mmu.c >>>>> +++ b/arch/arm/kvm/mmu.c >>>>> @@ -803,6 +803,7 @@ void stage2_unmap_vm(struct kvm *kvm) >>>>> int idx; >>>>> >>>>> idx = srcu_read_lock(&kvm->srcu); >>>>> + down_read(¤t->mm->mmap_sem); >>>>> spin_lock(&kvm->mmu_lock); >>>>> >>>>> slots = kvm_memslots(kvm); >>>>> @@ -810,6 +811,7 @@ void stage2_unmap_vm(struct kvm *kvm) >>>>> stage2_unmap_memslot(kvm, memslot); >>>>> >>>>> spin_unlock(&kvm->mmu_lock); >>>>> + up_read(¤t->mm->mmap_sem); >>>>> srcu_read_unlock(&kvm->srcu, idx); >>>>> } >>>>> >>>>> @@ -1813,6 +1815,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >>>>> * | memory region | >>>>> * +--------------------------------------------+ >>>>> */ >>>>> + down_read(¤t->mm->mmap_sem); >>>>> do { >>>>> struct vm_area_struct *vma = find_vma(current->mm, hva); >>>>> hva_t vm_start, vm_end; >>>> >>>> I have added the following hunk : >>>> >>>> @@ -1844,8 +1847,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >>>> pa += vm_start - vma->vm_start; >>>> >>>> /* IO region dirty page logging not allowed */ >>>> - if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) >>>> - return -EINVAL; >>>> + if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) { >>>> + ret = -EINVAL; >>>> + goto out; >>>> + } >>>> >>>> ret = kvm_phys_addr_ioremap(kvm, gpa, pa, >>>> vm_end - vm_start, >>>> >>> >>> Ah, of course... Thanks for pointing that out, I'll fix it as I post a >>> proper patch. >>> >>> Thanks, >>> >>> M. >>> -- >>> Jazz is not dead. It just smells funny... >> >> Hi, >> >> I've got this report again on linux-next 4c3c5cd02318 (Apr 5). >> >> It seems that it's still not fixed. >> >> Thanks! >> >> ================================================================== >> BUG: KASAN: use-after-free in vmacache_update+0x114/0x118 mm/vmacache.c:63 >> Read of size 8 at addr ffff80004d53aae8 by task syz-executor/23095 >> >> CPU: 0 PID: 23095 Comm: syz-executor Not tainted >> 4.11.0-rc5-next-20170405-xc2-09030-g4c3c5cd02318-dirty #4 > > The fixes went into -rc6. Can you please give it a go? Ah, OK, I assumed they were in the linux-next revision I used. Thanks! > > Thanks, > > M. > -- > Jazz is not dead. It just smells funny... > > -- > You received this message because you are subscribed to the Google Groups "syzkaller" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. From mboxrd@z Thu Jan 1 00:00:00 1970 From: andreyknvl@google.com (Andrey Konovalov) Date: Tue, 11 Apr 2017 17:41:35 +0200 Subject: kvm/arm64: use-after-free in kvm_vm_ioctl/vmacache_update In-Reply-To: References:

<3a57c408-8aa5-d339-4176-add4924e817d@arm.com> <0fc0380f-f108-7d20-ee8a-1b044fa1f115@arm.com> <2200dd06-2374-b95d-131b-5a2437d14007@arm.com> <7f9de429-d9e5-eb89-c72e-e002a65e8e0f@arm.com>

Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Apr 11, 2017 at 5:36 PM, Marc Zyngier wrote: > On 11/04/17 16:26, Andrey Konovalov wrote: >> On Tue, Mar 14, 2017 at 1:26 PM, Marc Zyngier wrote: >>> On 14/03/17 11:03, Suzuki K Poulose wrote: >>>> On 13/03/17 09:58, Marc Zyngier wrote: >>>>> On 10/03/17 18:37, Suzuki K Poulose wrote: >>>>>> On 10/03/17 15:50, Andrey Konovalov wrote: >>>>>>> On Fri, Mar 10, 2017 at 2:38 PM, Andrey Konovalov wrote: >>>>>>>> Hi, >>>>>>>> >>>>>>>> I've got the following error report while fuzzing the kernel with syzkaller. >>>>>>>> >>>>>>>> On linux-next commit 56b8bad5e066c23e8fa273ef5fba50bd3da2ace8 (Mar 8). >>>>>>>> >>>>>>>> Unfortunately I can't reproduce it. >>>>>>>> >>>>>>>> ================================================================== >>>>>>>> BUG: KASAN: use-after-free in vmacache_update+0x114/0x118 mm/vmacache.c:63 >>>>>>>> Read of size 8 at addr ffff80003b9a2040 by task syz-executor/26615 >>>>>>>> >>>>>>>> CPU: 1 PID: 26615 Comm: syz-executor Not tainted >>>>>>>> 4.11.0-rc1-next-20170308-xc2-dirty #3 >>>>>>>> Hardware name: Hardkernel ODROID-C2 (DT) >>>>>>>> Call trace: >>>>>>>> [] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:505 >>>>>>>> [] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:228 >>>>>>>> [] __dump_stack lib/dump_stack.c:16 [inline] >>>>>>>> [] dump_stack+0x110/0x168 lib/dump_stack.c:52 >>>>>>>> [] print_address_description+0x60/0x248 mm/kasan/report.c:250 >>>>>>>> [] kasan_report_error+0xe8/0x250 mm/kasan/report.c:349 >>>>>>>> [] kasan_report mm/kasan/report.c:372 [inline] >>>>>>>> [] __asan_report_load8_noabort+0x3c/0x48 mm/kasan/report.c:393 >>>>>>>> [] vmacache_update+0x114/0x118 mm/vmacache.c:63 >>>>>>>> [] find_vma+0xf8/0x150 mm/mmap.c:2124 >>>>>>>> [] kvm_arch_prepare_memory_region+0x2ac/0x488 >>>>>>>> arch/arm64/kvm/../../../arch/arm/kvm/mmu.c:1817 >>>>>>>> [] __kvm_set_memory_region+0x3d8/0x12b8 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1026 >>>>>>>> [] kvm_set_memory_region+0x38/0x58 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1075 >>>>>>>> [] kvm_vm_ioctl_set_memory_region >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:1087 [inline] >>>>>>>> [] kvm_vm_ioctl+0xb94/0x1308 >>>>>>>> arch/arm64/kvm/../../../virt/kvm/kvm_main.c:2960 >>>>>>>> [] vfs_ioctl fs/ioctl.c:45 [inline] >>>>>>>> [] do_vfs_ioctl+0x128/0xfc0 fs/ioctl.c:685 >>>>>>>> [] SYSC_ioctl fs/ioctl.c:700 [inline] >>>>>>>> [] SyS_ioctl+0xa8/0xb8 fs/ioctl.c:691 >>>>>>>> [] el0_svc_naked+0x24/0x28 >>>>>>>> >>>>>>>> Allocated by task 26657: >>>>>>>> save_stack_trace_tsk+0x0/0x330 arch/arm64/kernel/stacktrace.c:133 >>>>>>>> save_stack_trace+0x20/0x30 arch/arm64/kernel/stacktrace.c:216 >>>>>>>> save_stack mm/kasan/kasan.c:515 [inline] >>>>>>>> set_track mm/kasan/kasan.c:527 [inline] >>>>>>>> kasan_kmalloc+0xd4/0x180 mm/kasan/kasan.c:619 >>>>>>>> kasan_slab_alloc+0x14/0x20 mm/kasan/kasan.c:557 >>>>>>>> slab_post_alloc_hook mm/slab.h:456 [inline] >>>>>>>> slab_alloc_node mm/slub.c:2718 [inline] >>>>>>>> slab_alloc mm/slub.c:2726 [inline] >>>>>>>> kmem_cache_alloc+0x144/0x230 mm/slub.c:2731 >>>>>>>> __split_vma+0x118/0x608 mm/mmap.c:2515 >>>>>>>> do_munmap+0x194/0x9b0 mm/mmap.c:2636 >>>>>>>> Freed by task 26657: >>>>>>>> save_stack_trace_tsk+0x0/0x330 arch/arm64/kernel/stacktrace.c:133 >>>>>>>> save_stack_trace+0x20/0x30 arch/arm64/kernel/stacktrace.c:216 >>>>>>>> save_stack mm/kasan/kasan.c:515 [inline] >>>>>>>> set_track mm/kasan/kasan.c:527 [inline] >>>>>>>> kasan_slab_free+0x84/0x198 mm/kasan/kasan.c:592 >>>>>>>> slab_free_hook mm/slub.c:1357 [inline] >>>>>>>> slab_free_freelist_hook mm/slub.c:1379 [inline] >>>>>>>> slab_free mm/slub.c:2961 [inline] >>>>>>>> kmem_cache_free+0x80/0x258 mm/slub.c:2983 >>>>>>>> __vma_adjust+0x6b0/0xf mm/mmap.c:890] el0_svc_naked+0x24/0x28 >>>>>>>> >>>>>>>> The buggy address belongs to the object at ffff80003b9a2000 >>>>>>>> which belongs to the cache vm_area_struct(647:session-6.scope) of size 184 >>>>>>>> The buggy address is located 64 bytes inside of >>>>>>>> 184-byte region [ffff80003b9a2000, ffff80003b9a20b8) >>>>>>>> The buggy address belongs to the page: >>>>>>>> page:ffff7e0000ee6880 count:1 mapcount:0 mapping: (null) index:0x0 >>>>>>>> flags: 0xfffc00000000100(slab) >>>>>>>> raw: 0fffc00000000100 0000000000000000 0000000000000000 0000000180100010 >>>>>>>> raw: 0000000000000000 0000000c00000001 ffff80005a5cc600 ffff80005ac99980 >>>>>>>> page dumped because: kasan: bad access detected >>>>>>>> page->mem_cgroup:ffff80005ac99980 >>>>>>>> >>>>>>>> Memory state around the buggy address: >>>>>>>> ffff80003b9a1f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>>>>> ffff80003b9a1f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >>>>>>>>> ffff80003b9a2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>>>>>> ^ >>>>>>>> ffff80003b9a2080: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fb >>>>>>>> ffff80003b9a2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>>>>>> ================================================================== >>>>>>> >>>>>>> Another one that looks related and doesn't have parts of stack traces missing: >>>>>>> >>>>>>> ================================================================== >>>>>>> BUG: KASAN: use-after-free in find_vma+0x140/0x150 mm/mmap.c:2114 >>>>>>> Read of size 8 at addr ffff800031a03e90 by task syz-executor/4360 >>>>>>> >>>>>>> CPU: 2 PID: 4360 Comm: syz-executor Not tainted >>>>>>> 4.11.0-rc1-next-20170308-xc2-dirty #3 >>>>>>> Hardware name: Hardkernel ODROID-C2 (DT) >>>>>>> Call trace: >>>>>>> [] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:505 >>>>>>> [] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:228 >>>>>>> [] __dump_stack lib/dump_stack.c:16 [inline] >>>>>>> [] dump_stack+0x110/0x168 lib/dump_stack.c:52 >>>>>>> [] print_address_description+0x60/0x248 mm/kasan/report.c:250 >>>>>>> [] kasan_report_error+0xe8/0x250 mm/kasan/report.c:349 >>>>>>> [] kasan_report mm/kasan/report.c:372 [inline] >>>>>>> [] __asan_report_load8_noabort+0x3c/0x48 mm/kasan/report.c:393 >>>>>>> [] find_vma+0x140/0x150 mm/mmap.c:2114 >>>>>>> [] kvm_arch_prepare_memory_region+0x2ac/0x488 >>>>>>> arch/arm64/kvm/../../../arch/arm/kvm/mmu.c:1817 >>>>>> >>>>>> It looks like we don't take the mmap_sem before calling find_vma() in >>>>>> stage2_unmap_memslot() and in kvm_arch_prepare_memory_region(), which is causing >>>>>> the race, with probably the test trying to unmap ranges in between. >>>>> >>>>> That indeed seems like a possible failure mode. The annoying thing is >>>>> that we're not exactly in a position to take mmap_sem in >>>>> stage2_unmap_memslot, since we hold the kvm->mmu_lock spinlock. We may >>>>> have to hold mmap_sem while iterating over all the memslots. >>>>> >>>>> How about the following (very lightly tested): >>>>> >>>>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c >>>>> index 962616fd4ddd..2006a79d5912 100644 >>>>> --- a/arch/arm/kvm/mmu.c >>>>> +++ b/arch/arm/kvm/mmu.c >>>>> @@ -803,6 +803,7 @@ void stage2_unmap_vm(struct kvm *kvm) >>>>> int idx; >>>>> >>>>> idx = srcu_read_lock(&kvm->srcu); >>>>> + down_read(¤t->mm->mmap_sem); >>>>> spin_lock(&kvm->mmu_lock); >>>>> >>>>> slots = kvm_memslots(kvm); >>>>> @@ -810,6 +811,7 @@ void stage2_unmap_vm(struct kvm *kvm) >>>>> stage2_unmap_memslot(kvm, memslot); >>>>> >>>>> spin_unlock(&kvm->mmu_lock); >>>>> + up_read(¤t->mm->mmap_sem); >>>>> srcu_read_unlock(&kvm->srcu, idx); >>>>> } >>>>> >>>>> @@ -1813,6 +1815,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >>>>> * | memory region | >>>>> * +--------------------------------------------+ >>>>> */ >>>>> + down_read(¤t->mm->mmap_sem); >>>>> do { >>>>> struct vm_area_struct *vma = find_vma(current->mm, hva); >>>>> hva_t vm_start, vm_end; >>>> >>>> I have added the following hunk : >>>> >>>> @@ -1844,8 +1847,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, >>>> pa += vm_start - vma->vm_start; >>>> >>>> /* IO region dirty page logging not allowed */ >>>> - if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) >>>> - return -EINVAL; >>>> + if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) { >>>> + ret = -EINVAL; >>>> + goto out; >>>> + } >>>> >>>> ret = kvm_phys_addr_ioremap(kvm, gpa, pa, >>>> vm_end - vm_start, >>>> >>> >>> Ah, of course... Thanks for pointing that out, I'll fix it as I post a >>> proper patch. >>> >>> Thanks, >>> >>> M. >>> -- >>> Jazz is not dead. It just smells funny... >> >> Hi, >> >> I've got this report again on linux-next 4c3c5cd02318 (Apr 5). >> >> It seems that it's still not fixed. >> >> Thanks! >> >> ================================================================== >> BUG: KASAN: use-after-free in vmacache_update+0x114/0x118 mm/vmacache.c:63 >> Read of size 8 at addr ffff80004d53aae8 by task syz-executor/23095 >> >> CPU: 0 PID: 23095 Comm: syz-executor Not tainted >> 4.11.0-rc5-next-20170405-xc2-09030-g4c3c5cd02318-dirty #4 > > The fixes went into -rc6. Can you please give it a go? Ah, OK, I assumed they were in the linux-next revision I used. Thanks! > > Thanks, > > M. > -- > Jazz is not dead. It just smells funny... > > -- > You received this message because you are subscribed to the Google Groups "syzkaller" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe at googlegroups.com. > For more options, visit https://groups.google.com/d/optout.