| Message ID | 87czu4onry.ffs@nanos.tec.linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Cancel pvclock_gtod_work on module removal | expand |
On 05/05/21 23:48, Thomas Gleixner wrote: > Nothing prevents the following: > > pvclock_gtod_notify() > queue_work(system_long_wq, &pvclock_gtod_work); > ... > remove_module(kvm); > ... > work_queue_run() > pvclock_gtod_work() <- UAF > > Ditto for any other operation on that workqueue list head which touches > pvclock_gtod_work after module removal. > > Cancel the work in kvm_arch_exit() to prevent that. > > Fixes: 16e8d74d2da9 ("KVM: x86: notifier for clocksource changes") > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > Found by inspection because of: > https://lkml.kernel.org/r/0000000000001d43ac05c0f5c6a0@google.com > See also: > https://lkml.kernel.org/r/20210505105940.190490250@infradead.org > > TL;DR: Scheduling work with tk_core.seq write held is a bad idea. > --- > arch/x86/kvm/x86.c | 1 + > 1 file changed, 1 insertion(+) > > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -8168,6 +8168,7 @@ void kvm_arch_exit(void) > cpuhp_remove_state_nocalls(CPUHP_AP_X86_KVM_CLK_ONLINE); > #ifdef CONFIG_X86_64 > pvclock_gtod_unregister_notifier(&pvclock_gtod_notifier); > + cancel_work_sync(&pvclock_gtod_work); > #endif > kvm_x86_ops.hardware_enable = NULL; > kvm_mmu_module_exit(); > Queued, thanks (with added Cc to stable). Paolo
--- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8168,6 +8168,7 @@ void kvm_arch_exit(void) cpuhp_remove_state_nocalls(CPUHP_AP_X86_KVM_CLK_ONLINE); #ifdef CONFIG_X86_64 pvclock_gtod_unregister_notifier(&pvclock_gtod_notifier); + cancel_work_sync(&pvclock_gtod_work); #endif kvm_x86_ops.hardware_enable = NULL; kvm_mmu_module_exit();
Nothing prevents the following: pvclock_gtod_notify() queue_work(system_long_wq, &pvclock_gtod_work); ... remove_module(kvm); ... work_queue_run() pvclock_gtod_work() <- UAF Ditto for any other operation on that workqueue list head which touches pvclock_gtod_work after module removal. Cancel the work in kvm_arch_exit() to prevent that. Fixes: 16e8d74d2da9 ("KVM: x86: notifier for clocksource changes") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- Found by inspection because of: https://lkml.kernel.org/r/0000000000001d43ac05c0f5c6a0@google.com See also: https://lkml.kernel.org/r/20210505105940.190490250@infradead.org TL;DR: Scheduling work with tk_core.seq write held is a bad idea. --- arch/x86/kvm/x86.c | 1 + 1 file changed, 1 insertion(+)