From 0ea4ed8e948c30f88c824c973ee4b9529015fe65 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Wed, 14 Oct 2009 16:21:00 -0700 Subject: [PATCH] KVM: Prevent kvm_init from corrupting debugfs structures I'm seeing an oops condition when kvm-intel and kvm-amd are modprobe'd during boot (say on an Intel system) and then rmmod'd: # modprobe kvm-intel kvm_init() kvm_init_debug() kvm_arch_init() <-- stores debugfs dentries internally (success, etc) # modprobe kvm-amd kvm_init() kvm_init_debug() <-- second initialization clobbers kvm's internal pointers to dentries kvm_arch_init() kvm_exit_debug() <-- and frees them # rmmod kvm-intel kvm_exit() kvm_exit_debug() <-- double free of debugfs files! *BOOM* If execution gets to the end of kvm_init(), then the calling module has been established as the kvm provider. Move the debugfs initialization to the end of the function, and remove the now-unnecessary call to kvm_exit_debug() from the error path. That way we avoid trampling on the debugfs entries and freeing them twice. Cc: stable@kernel.org Signed-off-by: Darrick J. Wong Signed-off-by: Marcelo Tosatti --- virt/kvm/kvm_main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b7c78a403dc2..7495ce347344 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2717,8 +2717,6 @@ int kvm_init(void *opaque, unsigned int vcpu_size, int r; int cpu; - kvm_init_debug(); - r = kvm_arch_init(opaque); if (r) goto out_fail; @@ -2785,6 +2783,8 @@ int kvm_init(void *opaque, unsigned int vcpu_size, kvm_preempt_ops.sched_in = kvm_sched_in; kvm_preempt_ops.sched_out = kvm_sched_out; + kvm_init_debug(); + return 0; out_free: @@ -2807,7 +2807,6 @@ out_free_0: out: kvm_arch_exit(); out_fail: - kvm_exit_debug(); return r; } EXPORT_SYMBOL_GPL(kvm_init); @@ -2815,6 +2814,7 @@ EXPORT_SYMBOL_GPL(kvm_init); void kvm_exit(void) { tracepoint_synchronize_unregister(); + kvm_exit_debug(); misc_deregister(&kvm_dev); kmem_cache_destroy(kvm_vcpu_cache); sysdev_unregister(&kvm_sysdev); @@ -2824,7 +2824,6 @@ void kvm_exit(void) on_each_cpu(hardware_disable, NULL, 1); kvm_arch_hardware_unsetup(); kvm_arch_exit(); - kvm_exit_debug(); free_cpumask_var(cpus_hardware_enabled); __free_page(bad_page); } -- 2.30.2