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

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(a)redhat.com&gt;