[erlang-bugs] Unloading then reloading crypto.so causes erlang core dump on Solaris 11

[Sverker Eriksson]

XinFeng Liu wrote:
> Hi,
> I'm trying CouchDB (version 1.2) on Solaris 11 Sparc, but running CouchDB 
> testsuite in browser caused erlang process core dumped. I tried both erlang 
> 14B04 and 15B01.
> After investigation, I found it occurred when couchDB restarted itself. During 
> restarting, erlang unloaded crypto.so then reloaded it into a different address, 
> but openssl library libcrypto.so still using the old call back address 
> of  crypto_alloc() in lib/crypto/c_src/crypto.c. In fact, crypto_alloc() is 
> shown as a local function from "nm" command.
>
> The temporary workaround is modifying crypto.c:
> replace   CRYPTO_set_mem_functions(crypto_alloc, crypto_realloc, crypto_free);
> to:
>              CRYPTO_set_mem_functions(enif_alloc, enif_realloc, enif_free);
>
> I'm not sure it is erlang bug or bug of openssl  for solaris, please help clarify?
>   
This is crypto trying to do something which openssl does not support.

The workaround you suggested using enif_alloc instead of crypto_alloc 
seems like a good start if it solves your problem. There are however 
other callbacks for locking (see CRYPTO_set_locking_callback) that maybe 
could cause the same kind of problem.

The root problem is that openssl does not support "unregistering" of 
callbacks. The solution is probably some feature that would allow a NIF 
library to be kept in memory and be reused if/when the erlang module is 
loaded again.



XinFeng Liu wrote:
> I also tried another workaround in lib/crypto/c_src/crypto.c:
> add
> CRYPTO_set_mem_functions(crypto_alloc, crypto_realloc, crypto_free);
> in reload(ErlNifEnv* env, void** priv_data, ERL_NIF_TERM load_info) before 
> "return 0;"
> The couchDB testsuite runs fine.
> Is this way O.K.?
>
>   
This I don't understand at all.
reload() in crypto.c should only be called if the module is upgraded, 
not if it is unloaded and later loaded again.

/Sverker, Erlang/OTP