In message <1532398720.1344.206.ca...@freebsd.org>, Ian Lepore writes: > I don't think ssh is necessarily broken. It assumes pw_class will not > be NULL after a call to getpwnam(). That may be a fair assumption, > there's nothing in the manpage about it, but in practice the struct has > always been initialized to have pointers to empty strings. I changed > that so that one of them started getting chagned to a NULL pointer > without realizing it was breaking a sort of hidden implicit contract. > > I think the right fix is to make libutil's pw_scan() do the same thing > getpwnam() and other callers of __pw_scan() do, and init the struct to > have pointers to empty strings. And we should update some manpages to > make that an explicit contract.
My previous email. -- Cheers, Cy Schubert <cy.schub...@cschubert.com> FreeBSD UNIX: <c...@freebsd.org> Web: http://www.FreeBSD.org The need of the many outweighs the greed of the few. > > -- Ian > > On Mon, 2018-07-23 at 18:47 -0700, Cy Schubert wrote: > > 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.schub...@cschubert.com> or <c...@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-...@freebsd.org; svn-src-hea > > d...@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.schub...@cschubert.com> or <c...@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-...@freebsd.org; svn-src- > > > hea > > > d...@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.ca...@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.schub...@cschubert.com> or <c...@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 > > > _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
