dlsym(RTLD_NEXT) failures on ARM and MIPS with LD_PRELOAD w/ 0.9.33.2

[Florian Fainelli]

On Thursday 20 September 2012 22:09:52 Carmelo AMOROSO wrote:
> On 20/09/2012 8.36, Florian Fainelli wrote:
> > Hi all,
> > 
> 
> Hi Florian,

Hi Carmelo,

> 
> > I just updated two systems to uClibc 0.9.33.2/NPTL (ARMv5 and MIPS32r1), 
> > and I now see dlsym() returning NULL for a symbol where it should not.
> > 
> 
> Does it mean that with an older version is worked ? if so, which one ?
> it could help to identify the problem, if any.

The version we updated from was 0.9.30.2 which is quite old, I will start a 
bisection to pin point the exact commit introducing the issue.

> 
> > The situation is the following:
> > 
> > 1) application "foo" links against shared library "mylib" and in 
particular 
> > the symbol "bar"
> > 
> > 2) "mylib2" is a shared library providing a modified "bar" symbol and 
> > performing a dlsym(RTLD_NEXT, "bar") to get the "bar" symbol address in 
> > "mylib" and finally call this symbol.
> > 
> > 3) "foo" is started that way:
> > LD_PRELOAD="libmylib2.so" foo
> > 
> > I am yet to be able to write down a reduced test-case exposing the issue, 
> > because so far, the problem is appearing only in a much larger "mylib" and 
> > "foo" though they both do not do much more than what is described above. I 
> > have not tried uClibc's master yet.
> > 
> > Any hints would be appreciated 
> > 
> > Thanks!
> > 
> 
> cheers,
> Carmelo
> 
>