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| author | Darrick J. Wong <djwong@us.ibm.com> | 2009-10-14 16:21:00 -0700 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2009-10-16 12:30:26 -0300 |
| commit | 0ea4ed8e948c30f88c824c973ee4b9529015fe65 (patch) | |
| tree | b7bbcbc50fda3290c3acbb6ca38bd1e4dd3f05c6 /virt | |
| parent | 8a8365c560b8b631e0a2d1ac032fbca66a9645bc (diff) | |
| download | lwn-0ea4ed8e948c30f88c824c973ee4b9529015fe65.tar.gz lwn-0ea4ed8e948c30f88c824c973ee4b9529015fe65.zip | |
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 <djwong@us.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 7 |
1 files 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); } |