Re: [Patch nf] netfilter: xt_hashlimit: unregister proc file before releasing mutex

On Tue, Feb 18, 2020 at 01:40:26PM -0800, Cong Wang wrote:

On Tue, Feb 18, 2020 at 1:35 PM Pablo Neira Ayuso [off-list ref] wrote:

quoted

On Wed, Feb 12, 2020 at 10:53:52PM -0800, Cong Wang wrote:

quoted

Before releasing the global mutex, we only unlink the hashtable
from the hash list, its proc file is still not unregistered at
this point. So syzbot could trigger a race condition where a
parallel htable_create() could register the same file immediately
after the mutex is released.

Move htable_remove_proc_entry() back to mutex protection to
fix this. And, fold htable_destroy() into htable_put() to make
the code slightly easier to understand.

Probably revert previous one?

The hung task could appear again if we move the cleanup
back under mutex.

How could the hung task appear again by reverting
c4a3922d2d20c710f827? Please elaborate.

Thanks.