Re: [hurd, commited] hurd: Use __trivfs_server_name instead of trivfs_server_name

[Samuel Thibault]

Florian Weimer, le sam. 01 janv. 2022 19:48:21 +0100, a ecrit:
> * Samuel Thibault via Libc-alpha:
> >> > +  if (&__trivfs_server_name && __trivfs_server_name
> >> > +      && __trivfs_server_name[0] == 'r'
> >> > +      && __trivfs_server_name[1] == 'a'
> >> > +      && __trivfs_server_name[2] == 'n'
> >> > +      && __trivfs_server_name[3] == 'd'
> >> > +      && __trivfs_server_name[4] == 'o'
> >> > +      && __trivfs_server_name[5] == 'm'
> >> > +      && __trivfs_server_name[6] == '\0')
> >> >      /* We are random, don't try to read ourselves!  */
> >> >      return length;
> >> 
> >> How does this work?  It's a new synbol name, so there's no definition,
> >> so the weak reference is always null.
> >
> > It is peeking it from the program.
> >
> > Basically the problem is that the random translator uses glibc, whose
> > malloc implementation started using /dev/random in glibc 2.34, thus
> > reading itself.
> 
> I still don't understand.  Why isn't the condition always false?

The definition is in the random translator, which exports it in its
dynamic symbol table.

Samuel