[IGNITE-17922] C++ Thin: SIGSEGV on connection closed

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.14
• Fix Version/s: 2.15
• Component/s: thin client
• Release Note: C++ thin client: Fixrd SIGSEGV on connection closed
• Ignite Flags: Docs Required, Release Notes Required
• Assignee: Igor Sapego
• Reporter: Igor Sapego
• Created: 18/Oct/22 07:38
• Updated: 20/Apr/23 11:50
• Resolved: 18/Oct/22 08:30

Description

Let’s consider some simple program:

#include <ignite/thin/ignite_client.h>
#include <iostream>
#include <thread>
#include <chrono>

int main() {
    ignite::thin::IgniteClientConfiguration cfg;
    cfg.SetEndPoints("127.0.0.1");
    cfg.SetConnectionTimeout(2000);

    auto client = ignite::thin::IgniteClient::Start(cfg);

    auto cache = client.GetOrCreateCache<int64_t, int64_t>("person");

    try {
        while (true) {
            int64_t size;
            try {
                size = cache.GetSize(4);
                std::cout << size << "\n";

            } catch (ignite::IgniteError& e) {
                std::cerr << e.what() << "\n";
            }

            std::this_thread::sleep_for(std::chrono::milliseconds{1000});
        }
    } catch (...) {
        std::cerr << "Exception thrown\n";
    }
}

During server restart this program could crash because of data race.

It seems problem here: DataRouter::OnConnectionClosed.

void DataRouter::OnConnectionClosed(uint64_t id, const IgniteError* err)
            {
                SP_DataChannel channel;
                {
                    common::concurrent::CsLockGuard lock(channelsMutex);

                    channel = FindChannelLocked(id);

                    connectedChannels.erase(id);
                    InvalidateChannelLocked(channel);
                }

                channel.Get()->FailPendingRequests(err);
            }

Local variable channel initialized as nullptr, thus calling channel.Get()-> yields signal throw.

It seems FindChannelLocked call was unsuccessful, because objected was deleted in another thread (in this example most likely in main thread during GetSize)

I suggest WA to check SP_DataChannel state before dereferencing it.

Issue Links

• is duplicated by: IGNITE-17971 Nullptr access in thin c++ client in OnConnectionClosed
• links to: GitHub Pull Request #10325