2024-04-26 08:01:10

by David Howells

[permalink] [raw]
Subject: Re: [PATCH net] Fix a potential infinite loop in extract_user_to_sg()

Jakub Kicinski <[email protected]> wrote:

> On Thu, 25 Apr 2024 09:39:32 +0100 David Howells wrote:
> > Fix extract_user_to_sg() so that it will break out of the loop if
> > iov_iter_extract_pages() returns 0 rather than looping around forever.
>
> Is "goto fail" the right way to break out here?
> My intuition would be "break".
>
> On a quick read it seems like res = 0 may occur if we run out of
> iterator, is passing maxsize > iter->count illegal?

I would say that you're not allowed to ask for more than is in the iterator.
In a number of places this is called, it's a clear failure if you can't get
that the requested amount out of it - for example, if we're building a cifs
message and have set all the fields in the header and are trying to encrypt
the message.

David