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Destroy mempool on module exit to fix memory leak #23

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Destroy mempool on module exit to fix memory leak #23

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1 change: 1 addition & 0 deletions main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,7 @@ static void __exit khttpd_exit(void)
send_sig(SIGTERM, http_server, 1);
kthread_stop(http_server);
close_listen_socket(listen_socket);
mempool_destroy(http_buf_pool);

@cubic-dev-ai cubic-dev-ai Bot Aug 5, 2026

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P1: Destroying http_buf_pool on the exit path resolves the leak only if no worker thread is still using the pool at that moment. However, khttpd_exit() only stops the daemon thread (kthread_stop(http_server)); the per-connection http_server_worker kthreads spawned in http_server_daemon() are never tracked or stopped, so with an active connection a worker can still be blocked in recv holding a mempool_alloc'd buffer when mempool_destroy() frees the pool and runs http_buf_free on each element. The worker's later mempool_free(buf, http_buf_pool) then touches freed memory — converting the leak fix into a use-after-free/double-free (likely a crash) whenever unload happens with an open connection. Consider tracking all worker kthreads, stopping them (and draining/returning their buffers) before destroying the pool, so the destroy only runs once no in-flight buffers exist.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. At main.c, line 187:

<comment>Destroying `http_buf_pool` on the exit path resolves the leak only if no worker thread is still using the pool at that moment. However, `khttpd_exit()` only stops the daemon thread (`kthread_stop(http_server)`); the per-connection `http_server_worker` kthreads spawned in `http_server_daemon()` are never tracked or stopped, so with an active connection a worker can still be blocked in recv holding a `mempool_alloc`'d buffer when `mempool_destroy()` frees the pool and runs `http_buf_free` on each element. The worker's later `mempool_free(buf, http_buf_pool)` then touches freed memory — converting the leak fix into a use-after-free/double-free (likely a crash) whenever unload happens with an open connection. Consider tracking all worker kthreads, stopping them (and draining/returning their buffers) before destroying the pool, so the destroy only runs once no in-flight buffers exist.</comment>

<file context>
@@ -184,6 +184,7 @@ static void __exit khttpd_exit(void)
     send_sig(SIGTERM, http_server, 1);
     kthread_stop(http_server);
     close_listen_socket(listen_socket);
+    mempool_destroy(http_buf_pool);
     pr_info("module unloaded\n");
 }
</file context>

pr_info("module unloaded\n");
}

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