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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id p19sm1488014edr.73.2021.07.08.09.43.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Jul 2021 09:43:06 -0700 (PDT) Subject: Re: [PATCH] KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio To: Kefeng Wang , linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, Hulk Robot References: <20210626070304.143456-1-wangkefeng.wang@huawei.com> From: Paolo Bonzini Message-ID: <8c53acbe-ccb9-4283-0634-cbf69a1052e4@redhat.com> Date: Thu, 8 Jul 2021 18:43:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210626070304.143456-1-wangkefeng.wang@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/06/21 09:03, Kefeng Wang wrote: > BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183 > Read of size 8 at addr ffff0000c03a2500 by task syz-executor083/4269 > > CPU: 5 PID: 4269 Comm: syz-executor083 Not tainted 5.10.0 #7 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace+0x0/0x2d0 arch/arm64/kernel/stacktrace.c:132 > show_stack+0x28/0x34 arch/arm64/kernel/stacktrace.c:196 > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x110/0x164 lib/dump_stack.c:118 > print_address_description+0x78/0x5c8 mm/kasan/report.c:385 > __kasan_report mm/kasan/report.c:545 [inline] > kasan_report+0x148/0x1e4 mm/kasan/report.c:562 > check_memory_region_inline mm/kasan/generic.c:183 [inline] > __asan_load8+0xb4/0xbc mm/kasan/generic.c:252 > kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183 > kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755 > vfs_ioctl fs/ioctl.c:48 [inline] > __do_sys_ioctl fs/ioctl.c:753 [inline] > __se_sys_ioctl fs/ioctl.c:739 [inline] > __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739 > __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] > invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] > el0_svc_common arch/arm64/kernel/syscall.c:158 [inline] > do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220 > el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367 > el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383 > el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670 > > Allocated by task 4269: > stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121 > kasan_save_stack mm/kasan/common.c:48 [inline] > kasan_set_track mm/kasan/common.c:56 [inline] > __kasan_kmalloc+0xdc/0x120 mm/kasan/common.c:461 > kasan_kmalloc+0xc/0x14 mm/kasan/common.c:475 > kmem_cache_alloc_trace include/linux/slab.h:450 [inline] > kmalloc include/linux/slab.h:552 [inline] > kzalloc include/linux/slab.h:664 [inline] > kvm_vm_ioctl_register_coalesced_mmio+0x78/0x1cc arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:146 > kvm_vm_ioctl+0x7e8/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3746 > vfs_ioctl fs/ioctl.c:48 [inline] > __do_sys_ioctl fs/ioctl.c:753 [inline] > __se_sys_ioctl fs/ioctl.c:739 [inline] > __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739 > __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] > invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] > el0_svc_common arch/arm64/kernel/syscall.c:158 [inline] > do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220 > el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367 > el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383 > el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670 > > Freed by task 4269: > stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121 > kasan_save_stack mm/kasan/common.c:48 [inline] > kasan_set_track+0x38/0x6c mm/kasan/common.c:56 > kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:355 > __kasan_slab_free+0x124/0x150 mm/kasan/common.c:422 > kasan_slab_free+0x10/0x1c mm/kasan/common.c:431 > slab_free_hook mm/slub.c:1544 [inline] > slab_free_freelist_hook mm/slub.c:1577 [inline] > slab_free mm/slub.c:3142 [inline] > kfree+0x104/0x38c mm/slub.c:4124 > coalesced_mmio_destructor+0x94/0xa4 arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:102 > kvm_iodevice_destructor include/kvm/iodev.h:61 [inline] > kvm_io_bus_unregister_dev+0x248/0x280 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:4374 > kvm_vm_ioctl_unregister_coalesced_mmio+0x158/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:186 > kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755 > vfs_ioctl fs/ioctl.c:48 [inline] > __do_sys_ioctl fs/ioctl.c:753 [inline] > __se_sys_ioctl fs/ioctl.c:739 [inline] > __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739 > __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] > invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] > el0_svc_common arch/arm64/kernel/syscall.c:158 [inline] > do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220 > el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367 > el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383 > el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670 > > If kvm_io_bus_unregister_dev() return -ENOMEM, we already call kvm_iodevice_destructor() > inside this function to delete 'struct kvm_coalesced_mmio_dev *dev' from list > and free the dev, but kvm_iodevice_destructor() is called again, it will lead > the above issue. > > Let's check the the return value of kvm_io_bus_unregister_dev(), only call > kvm_iodevice_destructor() if the return value is 0. > > Cc: Paolo Bonzini > Cc: kvm@vger.kernel.org > Reported-by: Hulk Robot > Signed-off-by: Kefeng Wang > --- > virt/kvm/coalesced_mmio.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c > index f08f5e82460b..0be80c213f7f 100644 > --- a/virt/kvm/coalesced_mmio.c > +++ b/virt/kvm/coalesced_mmio.c > @@ -186,7 +186,6 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, > coalesced_mmio_in_range(dev, zone->addr, zone->size)) { > r = kvm_io_bus_unregister_dev(kvm, > zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev); > - kvm_iodevice_destructor(&dev->dev); > > /* > * On failure, unregister destroys all devices on the > @@ -196,6 +195,7 @@ int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm, > */ > if (r) > break; > + kvm_iodevice_destructor(&dev->dev); > } > } > > Queued, thanks. Paolo