Re: HelloWorld.c CRASHES when moved from FC6 to FC3!!

[Paul Pluzhnikov]

Ignoramus25565 <ignoramus25565@NOSPAM.25565.invalid> writes:

> Seems to work.

I've reproduced the crash when compiling "int main() { return 0; }"
on FC6 and running it on FC4.

The reason dynamic linker crashes is that a.out doesn't have
DT_HASH dynamic tag at all, and FC4 ld-linux.so.2 expects it (and
divides by l_nbuckets (zero) without checking):

#0  0x00991898 in dl_main (phdr=0x8048034, phnum=224, user_entry=0xbffff64c) at 
rtld.c:1360
1360          for (symidx = main_map->l_buckets[0x6c994f % 
main_map->l_nbuckets];

Compiling the same code on FC6 with '-Wl,--hash-style=sysv' fixes
that crash.

Still you are on dangerous ground -- your exe may have subtle
and non-trivial bugs introduced by "backward" compilation
environment. Let's hope you have adequate regression tests ...

> Also, interestingly, not only the app used to fail witi SIGFPE, but
> also "ldd app". 

That's not surprising at all -- "ldd" is a simple shell script,
which tells ld-linux.so.2 to print libraries instead of actually
loading them. The root cause of the crash is the same in both cases:
missing DT_HASH dynamic tag.

Cheers,
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