[rfa/gdbserver] Updated: Fix crash in thread_db_get_tls_address

Ulrich Weigand
2009-04-03T18:07:06Z

Doug Evans wrote:
> On Thu, Jan 22, 2009 at 7:05 AM, Ulrich Weigand <uweigand@de.ibm.com> wrote:
> > Doug Evans wrote:
> >
> >> Hi. I've run into similar situations with the thread layer not yet
> >> initialized. One aspect of this patch is a bit confusing. Maybe a
> >> comment is warranted.
> >>
> >> Returning -1 will cause server.c:handle_query to mark the packet as
> >> unknown which will in turn cause remote.c:packet_ok to mark the packet
> >> as disabled (on the gdb side). How does the packet get re-enabled if
> >> the thread layer is later initialized?
> >
> > You're right -- I missed that. I guess we need to report an error
> > instead of marking the packet as unknown.
> >
> > The following patch is changed to use TD_ERR ("generic error" seems to
> > be the best response -- I don't see a more specific code that would be
> > appropriate here).
> >
> > Retested on powerpc64-linux (64-bit / 32-bit) with local gdbserver.
>
> I don't know if there's a better value to use here either. Maybe
> TD_TLSDEFER, but I'm just guessing (and I don't know how portable it
> is).

TD_TLSDEFER doesn't seem to be available everywhere, and has a somewhat
different meaning, I think. In any case, it doesn't really matter, as GDB
will currently throw a TLS_GENERIC_ERROR in remote.c no matter what error
code is returned ...

I've updated the patch to account for multi-process changes.
Retested on powerpc64-linux (64-bit / 32-bit) with local gdbserver.

Dan, is this OK for mainline?

Bye,
Ulrich

ChangeLog:

* thread-db.c (thread_db_get_tls_address): Do not crash if
called when thread layer is not yet initialized.

Index: src/gdb/gdbserver/thread-db.c
===================================================================
--- src.orig/gdb/gdbserver/thread-db.c
+++ src/gdb/gdbserver/thread-db.c
@@ -382,6 +382,10 @@ thread_db_get_tls_address (struct thread
struct lwp_info *lwp;
struct thread_info *saved_inferior;

+ /* If the thread layer is not (yet) initialized, fail. */
+ if (!current_process()->all_symbols_looked_up)
+ return TD_ERR;
+
lwp = get_thread_lwp (thread);
if (!lwp->thread_known)
find_one_thread (lwp->head.id);