On Mon, Nov 11, 2019 at 5:25 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > Reported by syzkaller: > > ============================= > WARNING: suspicious RCU usage > ----------------------------- > ./include/linux/kvm_host.h:536 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > no locks held by repro_11/12688. > > stack backtrace: > Call Trace: > dump_stack+0x7d/0xc5 > lockdep_rcu_suspicious+0x123/0x170 > kvm_dev_ioctl+0x9a9/0x1260 [kvm] > do_vfs_ioctl+0x1a1/0xfb0 > ksys_ioctl+0x6d/0x80 > __x64_sys_ioctl+0x73/0xb0 > do_syscall_64+0x108/0xaa0 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > Commit a97b0e773e4 (kvm: call kvm_arch_destroy_vm if vm creation fails) > sets users_count to 1 before kvm_arch_init_vm(), however, if kvm_arch_init_vm() > fails, we need to decrease this count. By moving it earlier, we can push > the decrease to out_err_no_arch_destroy_vm without introducing yet another > error label. > > syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=15209b84e00000 > > Reported-by: syzbot+75475908cd0910f141ee@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: a97b0e773e49 ("kvm: call kvm_arch_destroy_vm if vm creation fails") > Cc: Jim Mattson <jmattson@xxxxxxxxxx> > Analyzed-by: Wanpeng Li <wanpengli@xxxxxxxxxxx> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
