[issue1863] Implement 'hammer volume-list' subcommand

[Stathis Kamperis (via DragonFly issue tracker)]

Stathis Kamperis <ekamperi at gmail.com> added the comment:

Short follow-up.

Matt commented on the code in IRC and said that there should a validation of
sizeof(struct hammer_ioc_volume). Otherwise the hammer vfs might overflow the
data buffer, the userland provides.

Although Matt was kind enough to explain it twice, I still don't get it. I'm
allocating room for the maximum volumes a file system can have and also I'm only
writing to the 'device_name' field of 'hammer_ioc_volume' structure, which
happens to have automatic storage.

So, what kind of buffer overrun I should be checking against? Can anyone please
provide some code  snippet or an insight ?

Thanks!
Stathis

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status: unread -> chatting

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