Date: Mon, 23 Jul 2018 18:05:26 -0600 From: Ian Lepore <ian@freebsd.org> To: Cy Schubert <Cy.Schubert@cschubert.com> Cc: Alan Somers <asomers@freebsd.org>, src-committers <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r336619 - head/lib/libc/gen Message-ID: <1532390726.1344.194.camel@freebsd.org> In-Reply-To: <20180723235258.2DB5EC73@spqr.komquats.com> References: <20180723235258.2DB5EC73@spqr.komquats.com>
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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@cschubert.com> or <cy@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@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.camel@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@cschubert.com> or <cy@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 >
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