[PATCH] fhandler_pipe: add sanity limit to handle loops

[Jeremy Drake]

On Sun, 26 Dec 2021, Ken Brown wrote:

> On 12/26/2021 11:04 AM, Ken Brown wrote:
> > On 12/26/2021 10:09 AM, Ken Brown wrote:
> > > 1. For some processes, NtQueryInformationProcess(ProcessHandleInformation)
> > > can return STATUS_SUCCESS with invalid handle information.  See the
> > > comment starting at line 5754, where it is shown how to detect this.

I kind of thought something like this (that NumberOfHandles was
uninitialized memory).

> > If I'm right, the following patch should fix the problem:
> >
> > diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
> > index ba6b70f55..4cef3e4ca 100644
> > --- a/winsup/cygwin/fhandler_pipe.cc
> > +++ b/winsup/cygwin/fhandler_pipe.cc
> > @@ -1228,6 +1228,7 @@ fhandler_pipe::get_query_hdl_per_process (WCHAR *name,
> >              HeapAlloc (GetProcessHeap (), 0, nbytes);
> >            if (!phi)
> >              goto close_proc;
> > +         phi->NumberOfHandles = 0;
> >            status = NtQueryInformationProcess (proc,
> > ProcessHandleInformation,
> >                                                phi, nbytes, &len);
> >            if (NT_SUCCESS (status))
>
> Actually, this first hunk should suffice.
>
> > Jeremy, could you try this?
> >
> > Ken


I've built (leaving the assert in place too), and I've got 3 loops going
on server 2022 and 1 going on ARM64.  So far so good.  I don't know how
long before calling it good though.