[PATCH 05/14] fs: don't allow kernel reads and writes without iter ops

[Linus Torvalds]

On Fri, Oct 9, 2020 at 6:19 PM Eric Biggers <ebiggers at kernel.org> wrote:
>
> Okay, that makes more sense.  So the patchset from Matthew
> https://lkml.kernel.org/linux-fsdevel/20201003025534.21045-1-willy@infradead.org/T/#u
> isn't what you had in mind.

No.

That first patch makes sense - it's just the "ppos can be NULL" patch.

But as mentioned, NULL isn't "shorthand for zero". It's just "pipes
don't _have_ a pos, trying to pass in some explicit position is
crazy".

So no, the other patches in that set are a bit odd, I think.

SOME of them look potentially fine - the bpfilter one seems to be
valid, for example, because it's literally about reading/writing a
pipe. And maybe the sysctl one is similarly sensible - I didn't check
the context of that one.

But no, NULL shouldn't mean "start at position zero, and we don't care
about the result".

              Linus