| Message ID | 1572848879-21011-1-git-send-email-wanpengli@tencent.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] KVM: Fix NULL-ptr defer after kvm_create_vm fails | expand |
On 04/11/19 07:27, Wanpeng Li wrote: > Commit 9121923c457d ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm") > moves memslots and buses allocations around, however, if kvm->srcu/irq_srcu fails > initialization, NULL will be returned instead of error code, NULL will not be intercepted > in kvm_dev_ioctl_create_vm() and be deferenced by kvm_coalesced_mmio_init(), this patch > fixes it. This is not enough, as syzkaller also reported an incorrect synchronize_srcu that was also reported by syzkaller: wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 __synchronize_srcu+0x197/0x250 kernel/rcu/srcutree.c:921 synchronize_srcu_expedited kernel/rcu/srcutree.c:946 [inline] synchronize_srcu+0x239/0x3e8 kernel/rcu/srcutree.c:997 kvm_page_track_unregister_notifier+0xe7/0x130 arch/x86/kvm/page_track.c:212 kvm_mmu_uninit_vm+0x1e/0x30 arch/x86/kvm/mmu.c:5828 kvm_arch_destroy_vm+0x4a2/0x5f0 arch/x86/kvm/x86.c:9579 kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:702 [inline] I'm thinking of something like this (not tested yet): diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d6f0696d98ef..e22ff63e5b1a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -645,6 +645,11 @@ static struct kvm *kvm_create_vm(unsigned long type) BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX); + if (init_srcu_struct(&kvm->srcu)) + goto out_err_no_srcu; + if (init_srcu_struct(&kvm->irq_srcu)) + goto out_err_no_irq_srcu; + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { struct kvm_memslots *slots = kvm_alloc_memslots(); @@ -675,11 +680,6 @@ static struct kvm *kvm_create_vm(unsigned long type) INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list); #endif - if (init_srcu_struct(&kvm->srcu)) - goto out_err_no_srcu; - if (init_srcu_struct(&kvm->irq_srcu)) - goto out_err_no_irq_srcu; - r = kvm_init_mmu_notifier(kvm); if (r) goto out_err; @@ -693,10 +693,6 @@ static struct kvm *kvm_create_vm(unsigned long type) return kvm; out_err: - cleanup_srcu_struct(&kvm->irq_srcu); -out_err_no_irq_srcu: - cleanup_srcu_struct(&kvm->srcu); -out_err_no_srcu: hardware_disable_all(); out_err_no_disable: kvm_arch_destroy_vm(kvm); @@ -706,6 +702,10 @@ static struct kvm *kvm_create_vm(unsigned long type) kfree(kvm_get_bus(kvm, i)); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) kvm_free_memslots(kvm, __kvm_memslots(kvm, i)); + cleanup_srcu_struct(&kvm->irq_srcu); +out_err_no_irq_srcu: + cleanup_srcu_struct(&kvm->srcu); +out_err_no_srcu: kvm_arch_free_vm(kvm); mmdrop(current->mm); return ERR_PTR(r); Paolo
On 04.11.19 07:27, Wanpeng Li wrote: > From: Wanpeng Li <wanpengli@tencent.com> > > Reported by syzkaller: > > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 14727 Comm: syz-executor.3 Not tainted 5.4.0-rc4+ #0 > RIP: 0010:kvm_coalesced_mmio_init+0x5d/0x110 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:121 > Call Trace: > kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:3446 [inline] > kvm_dev_ioctl+0x781/0x1490 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3494 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:509 [inline] > do_vfs_ioctl+0x196/0x1150 fs/ioctl.c:696 > ksys_ioctl+0x62/0x90 fs/ioctl.c:713 > __do_sys_ioctl fs/ioctl.c:720 [inline] > __se_sys_ioctl fs/ioctl.c:718 [inline] > __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:718 > do_syscall_64+0xca/0x5d0 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Commit 9121923c457d ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm") > moves memslots and buses allocations around, however, if kvm->srcu/irq_srcu fails > initialization, NULL will be returned instead of error code, NULL will not be intercepted > in kvm_dev_ioctl_create_vm() and be deferenced by kvm_coalesced_mmio_init(), this patch > fixes it. > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13509b84e00000 > > Reported-by: syzbot+89a8060879fa0bd2db4f@syzkaller.appspotmail.com > Fixes: 9121923c457d ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm") > Cc: Jim Mattson <jmattson@google.com> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> > --- > virt/kvm/kvm_main.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index d6f0696..8c272eb 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -675,6 +675,7 @@ static struct kvm *kvm_create_vm(unsigned long type) > INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list); > #endif > > + r = -ENOMEM; > if (init_srcu_struct(&kvm->srcu)) > goto out_err_no_srcu; > if (init_srcu_struct(&kvm->irq_srcu)) >
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d6f0696..8c272eb 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -675,6 +675,7 @@ static struct kvm *kvm_create_vm(unsigned long type) INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list); #endif + r = -ENOMEM; if (init_srcu_struct(&kvm->srcu)) goto out_err_no_srcu; if (init_srcu_struct(&kvm->irq_srcu))