[Crash-utility] [PATCH 1/2] Change functions in extensions/echo.c to be static

[HAGIO KAZUHITO(萩尾 一仁)]

-----Original Message-----
> 在 2021年04月02日 08:45, HAGIO KAZUHITO(萩尾　一仁) 写道:
> > -----Original Message-----
> >> If a same extension(Eg: extensions/trace.so) with two different names are loaded by
> >> "extend" command twice, it sometimes segfaults crash.
> >>
> >> It's because crash uses RTLD_NOW|RTLD_GLOBAL flags of dlopen to load an extension.
> >> RTDL_GLOBAL will make symbols defined by this shared object available for
> >> symbol resolution of subsequently loaded shared objects. So symbols in subsequently
> >> loaded extensions are overwritten by the former loaded one with a same name.
> >> Not only can it cause segfaults, but some other unexpected behaviours.
> >
> > The phenomenon of the first paragraph is an example and a rare situation if
> > not on purpose, please let me change the order and generalize a bit more here:
> > ---
> > The crash utility uses RTLD_NOW|RTLD_GLOBAL flags ... with the same name.
> >
> > This can cause unexpected behaviors when loading two extension modules that
> > have a symbol with the same name.  For example, we can reproduce a segmentation
> > violation by loading the current trace.so extension module with two different
> > names.
> > ---
> >
> > I'll edit when applying.  Otherwise, the patch looks good to me.
> 
> This change looks good. For the [PATCH 1/2] Change functions in extensions/echo.c to be static
> 
> Acked-by: Lianbo Jiang <lijiang at redhat.com>

Applied with a few editing:
https://github.com/crash-utility/crash/commit/506da42

Thanks,
Kazu