Crash "free(): invalid pointer" in sock.read() in a separate task

[ttaubert]

I compiled a little tcp listener example that spawns tasks per connection. The sock.read() call fails when it receives data - just use telnet to connect, type something and hit enter:

extern mod std;

use std::uv;
use std::net::{ip, tcp};

fn main() {
  let iotask = uv::global_loop::get();
  let addr = ip::v4::parse_addr("127.0.0.1");

  tcp::listen(addr, 4000u, 128u, iotask,
    |kill_ch| {
      #info("server is listening");
    },

    |new_conn, kill_ch| {
      let port = comm::Port::<()>();
      let chan = port.chan();

      do task::spawn_sched(task::ManualThreads(1u)) {
        let accept_result = tcp::accept(new_conn);
        chan.send(());

        if accept_result.is_err() {
          let err_data = result::unwrap_err(accept_result);
          kill_ch.send(Some(err_data));
        } else {
          let sock = result::unwrap(accept_result);
          let read_result = sock.read(0);
          if read_result.is_ok() {
            io::println("success");
          } else {
            kill_ch.send(None);
          }
        }
      }

      chan.recv();
    }
  );
}

This used to work with Rust 0.3 but crashes now with the following message:

*** glibc detected *** ./test: free(): invalid pointer: 0x00007f94c41027a8 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x7ec96)[0x7f94cd920c96]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x36e6d)[0x7f94cdeade6d]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(upcall_call_shim_on_c_stack+0x87)[0x7f94cde97cd7]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.4.so(+0x63210)[0x7f94cdf44210]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x36e6d)[0x7f94cdeade6d]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(upcall_call_shim_on_rust_stack+0xcf)[0x7f94cde97fff]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.4.so(+0x60a95)[0x7f94cdf41a95]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x3af77)[0x7f94cdeb1f77]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x4099f)[0x7f94cdeb799f]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x458b8)[0x7f94cdebc8b8]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x37d12)[0x7f94cdeaed12]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(+0x36e6d)[0x7f94cdeade6d]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(upcall_call_shim_on_c_stack+0x87)[0x7f94cde97cd7]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.4.so(+0x78b6e)[0x7f94cdf59b6e]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.4.so(+0x7ea0e)[0x7f94cdf5fa0e]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.4.so(+0xe8710)[0x7f94cdfc9710]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libcore-c3ca5d77d81b46c1-0.4.so(_ZN7private11weaken_task17_a2f0b02d17df416d3_04E+0xd2)[0x7f94ce150fe2]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libstd-4782a756585a81-0.4.so(+0x7e4b9)[0x7f94cdf5f4b9]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libcore-c3ca5d77d81b46c1-0.4.so(+0x76322)[0x7f94ce136322]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/libcore-c3ca5d77d81b46c1-0.4.so(+0xb6000)[0x7f94ce176000]
/home/tim/workspace/rust-memcached/../../../../usr/local/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f94cde960e4]

[ttaubert]

Any update here? This is blocking even the simplest server app.

[brson]

Is this on a 32-bit system by chance? uv is completely broken there due to FFI bugs.

[brson]

Oh, it's obviously a 64-bit system based on the logs. Hm.

[erickt]

@ttaubert: It's working on OSX lion for me, and I have heard that it's working on an ubuntu 12.04 x86_64 box. What platform are you running into this on, and is it still occurring on the latest incoming branch?

[ttaubert]

Thanks for the quick response, I'm on Ubuntu 12.04 as well. Will try the latest incoming branch and report back.

[ttaubert]

The provided test file still crashes for me with the latest incoming.

[erickt]

@ttaubert any chance you can hop in our irc channel #rust on irc.mozilla.org? You can use this link if you don't already have a client set up.

[ttaubert]

So in the middle of trying to reproduce this it suddenly stopped occuring. I have no idea why. Closing for now.

[brson]

There's been another report of this error.

[brson]

Won't be fixed in 0.6

[graydon]

Closing this one as WONTFIX, the underlying APIs here are going to be removed when we shift to the new scheduler (shortly), and we have no reports (yet) of such issues in the new scheduler. Sorry, limited time :(