svn commit: r336619 - head/lib/libc/gen

[Cy Schubert]

Well, the ssh client is still broken and IMO needs to be fixed sooner than later. If we want to maintain compatibility right now before any rewrite is attempted, our options are limited. Just saying that if this will be broken for a while we need some kind of workaround. Instead of a null pointer a pointer to a statically defined null string. I know it's ugly and hate to suggest it but it gives us (you) more time for a better solution.

BTW, I agree about the whack-a-mole thing given the brokenness.

---
Sent using a tiny phone keyboard.
Apologies for any typos and autocorrect.
Also, this old phone only supports top post. Apologies.

Cy Schubert
<Cy.Schubert at cschubert.com> or <cy at freebsd.org>
The need of the many outweighs the greed of the few.
---

-----Original Message-----
From: Ian Lepore
Sent: 23/07/2018 17:05
To: Cy Schubert
Cc: Alan Somers; src-committers; svn-src-all at freebsd.org; svn-src-head at freebsd.org
Subject: Re: svn commit: r336619 - head/lib/libc/gen

I don't wanna play whack-a-mole like that. This whole area is a great
big mess, and it needs a great big cleanup, and I've got too many other
irons in the fire right now to do that.

-- Ian

On Mon, 2018-07-23 at 16:52 -0700, Cy Schubert wrote:
> I think you misunderstood me because of my terse email. Sorry about
> that. We can address this with a NULL check in openssh's misc.c. I
> can't recall the actual path. I'll post a patch, which will explain
> it better than I can in English, as soon as I get home.
> 
> ---
> Sent using a tiny phone keyboard.
> Apologies for any typos and autocorrect.
> Also, this old phone only supports top post. Apologies.
> 
> Cy Schubert
> <Cy.Schubert at cschubert.com> or <cy at freebsd.org>
> The need of the many outweighs the greed of the few.
> ---
> 
> -----Original Message-----
> From: Ian Lepore
> Sent: 23/07/2018 13:40
> To: Cy Schubert
> Cc: Alan Somers; src-committers; svn-src-all at freebsd.org; svn-src-hea
> d at freebsd.org
> Subject: Re: svn commit: r336619 - head/lib/libc/gen
> 
> On Mon, 2018-07-23 at 13:11 -0700, Cy Schubert wrote:
> > 
> > In message <1532364679.1344.161.camel at freebsd.org>, Ian Lepore
> > writes:
> > > 
> > > 
> > > On Mon, 2018-07-23 at 09:41 -0700, Cy Schubert wrote:
> > > > 
> > > > 
> > > > I'm sure. Rolling this libc commit back addressed the ssh
> > > > segfaults
> > > > on all my systems.
> > > > 
> > > > ---
> > > > Sent using a tiny phone keyboard.
> > > > Apologies for any typos and autocorrect.
> > > > Also, this old phone only supports top post. Apologies.
> > > > 
> > > > Cy Schubert
> > > > <Cy.Schubert at cschubert.com> or <cy at freebsd.org>
> > > > The need of the many outweighs the greed of the few.
> > > > ---
> > > > 
> > > My current working theory is that some of the software that uses
> > > __pw_scan() pre-stages a pointer-to-empty-string into the
> > > pw_class
> > > field and my change ruined that by replacing it with a NULL
> > > pointer.
> > > Other callers of __pw_scan() don't do that, they just assume
> > > they're
> > > running as root and will get all the fields populated.
> > Yes. A simple check for pw->pw_class != NULL should fix this
> > instance.
> > 
> > 
> No, that doesn't work, because __pw_scan just skips setting pw_class
> and that leaves non-NULL garbage in that pointer.  There is a
> pw_fields
> field that uses bits to indicate which fields were parsed, but almost
> nothing uses it, so I'm reluctant to rely on it because this same
> kind
> of unexpected crash of some random tool will happen if there's
> anything
> that fills out a pwd struct without making those flags valid then
> calls
> pw_copy() which would rely on them being valid.
> 
> I've decided that the only safe way to fix this is to have pw_scan()
> do
> the same thing getpwnam() and friends do:  first init the pwd struct
> to
> known values, including supplying empty strings rather than NULL
> pointers for all the char* fields, before calling __pw_scan().
> 
> But, all of a sudden I've gotten busy with $work, so I may have to
> set
> all this aside for a few days.
> 
> -- Ian
>