Commits
Masamitsu Yamazaki committed bd1c06a4f5e
ipmi: Clear smi_info->thread to prevent use-after-free during module unload During code inspection, I found an use-after-free possibility during unloading ipmi_si in the polling mode. If start_new_msg() is called after kthread_stop(), the function will try to wake up non-existing kthread using the dangling pointer. Possible scenario is when a new internal message is generated after ipmi_unregister_smi()[*1] and remains after stop_timer_and_thread() in clenaup_one_si() [*2]. Use-after-free could occur as follows depending on BMC replies. cleanup_one_si => ipmi_unregister_smi [*1] => stop_timer_and_thread => kthread_stop(smi_info->thread) [*2] => poll => smi_event_handler => start_new_msg => if (smi_info->thread) wake_up_process(smi_info->thread) <== use-after-free!! Although currently it seems no such message is generated in the polling mode, some changes might introduce that in thefuture. For example in the interrupt mode, disable_si_irq() does that at [*2]. So let's prevent such a critical issue possibility now. Signed-off-by: Yamazaki Masamitsu <m-yamazaki@ah.jp.nec.com> Signed-off-by: Corey Minyard <cminyard@mvista.com>