[pkg-fso-maint] Bug#766114: Bug#766114: Aw: Re: Bug#766114: Bug#766114: fso-deviced: uninstallable in i386/amd64/armhf

[Sebastian Reichel]

Hi,

Sorry for the long time to answer, but I had no time to dig into
this.

On Thu, Nov 06, 2014 at 10:40:39PM +0100, hikaru.debian at web.de wrote:
> > Hmm, it's a strange thing. If I recompile fso-deviced eveything works as 
> > expected.
> 
> But you can reproduce the problem with the packages as they are in
> Debian right now?
> I just rebuild the Jessie package (armhf) and still get the same
> startup error (as I expected).

I can verify, that the binary is broken (and thus the init script
fails, too).

> > It seems, the generated .c files from vala-sources are broken.
> 
> Unfortunately this is above my skills. Please let me know if I can be of any
> further assistance in solving this!

starting the binary without the init script tells us:

$ sudo fsodeviced
*** stack smashing detected ***: fsodeviced terminated
[...]

Which means, that there is a stack based buffer overflow. I could
trace the problem to the Kernel.InputDevice constructor method,
which is kernel_input_device_construct() in the plugin.c

I guess Rico does not use the "-fstack-protector-strong" gcc
parameter, so in his build setup the binary does not verify if the
stack has been corrupted.

Stuff I tried so far to find the stack problem:

* comparing the generated C code from current vala with the
  pregenerated C code from FSO:
  problem has not been introduced by newer vala!
* reading through the C code to find the stack problem:
  could not find it!
* runing binary without -fstack-protector-strong in valgrind:
  nothing found in the Kernel.InputDevice constructor
* building without -O2:
  works
* build using clang-3.5 without changing CFLAGS/LDFLAGS
  still broken
* build using clang-3.5 + address sanitizer:
  problem gone :( [it would have traced the error]

So I think I will enable "-fno-stack-protector" in the package
for now.

-- Sebastian
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