On Thu, Sep 19, 2019 at 10:58:06AM +0800, Xiaoming Ni wrote:
> Registering the same notifier to a hook repeatedly can cause the hook
> list to form a ring or lose other members of the list.
>
> case1: An infinite loop in notifier_chain_register() can cause soft lockup
> atomic_notifier_chain_register(&test_notifier_list, &test1);
> atomic_notifier_chain_register(&test_notifier_list, &test1);
> atomic_notifier_chain_register(&test_notifier_list, &test2);
>
> case2: An infinite loop in notifier_chain_register() can cause soft lockup
> atomic_notifier_chain_register(&test_notifier_list, &test1);
> atomic_notifier_chain_register(&test_notifier_list, &test1);
> atomic_notifier_call_chain(&test_notifier_list, 0, NULL);
>
> case3: lose other hook test2
> atomic_notifier_chain_register(&test_notifier_list, &test1);
> atomic_notifier_chain_register(&test_notifier_list, &test2);
> atomic_notifier_chain_register(&test_notifier_list, &test1);
>
> case4: Unregister returns 0, but the hook is still in the linked list,
> and it is not really registered. If you call notifier_call_chain
> after ko is unloaded, it will trigger oops.
>
> If the system is configured with softlockup_panic and the same
> hook is repeatedly registered on the panic_notifier_list, it
> will cause a loop panic.
>
> Add a check in notifier_chain_register(),
> Intercepting duplicate registrations to avoid infinite loops
>
> Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> Reviewed-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
> ---
> kernel/notifier.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
Same thing goes for all of the patches in this series.
thanks,
greg k-h
