From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
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 dec this count. Or, we can move the sets refcount after
kvm_arch_init_vm().
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>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d6f0696..62ae0c9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -662,11 +662,11 @@ static struct kvm *kvm_create_vm(unsigned long type)
goto out_err_no_arch_destroy_vm;
}
- refcount_set(&kvm->users_count, 1);
r = kvm_arch_init_vm(kvm, type);
if (r)
goto out_err_no_arch_destroy_vm;
+ refcount_set(&kvm->users_count, 1);
r = hardware_enable_all();
if (r)
goto out_err_no_disable;
--
2.7.4
