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bd1c06a4f5
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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.