Memory usage after free

[splitice]

We upgraded to a newer openresty and begun to see segfaults.

Valgrind output:

==32455== Invalid read of size 8
==32455==    at 0x20C72D: ngx_thread_pool_handler (ngx_thread_pool.c:387)
==32455==    by 0x20A923: ngx_epoll_notify_handler (ngx_epoll_module.c:456)
==32455==    by 0x20B47B: ngx_epoll_process_events (ngx_epoll_module.c:901)
==32455==    by 0x1FACE4: ngx_process_events_and_timers (ngx_event.c:247)
==32455==    by 0x208F79: ngx_worker_process_cycle (ngx_process_cycle.c:750)
==32455==    by 0x205988: ngx_spawn_process (ngx_process.c:199)
==32455==    by 0x207FC4: ngx_start_worker_processes (ngx_process_cycle.c:359)
==32455==    by 0x207692: ngx_master_process_cycle (ngx_process_cycle.c:131)
==32455==    by 0x1C6789: main (nginx.c:382)
==32455==  Address 0x88cb6c0 is 0 bytes inside a block of size 192 free'd
==32455==    at 0x48369AB: free (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==32455==    by 0x1CA22F: ngx_destroy_pool (ngx_palloc.c:85)
==32455==    by 0x39FC7C: ngx_http_lua_close_fake_connection (ngx_http_lua_util.c:3812)
==32455==    by 0x39FA77: ngx_http_lua_close_fake_request (ngx_http_lua_util.c:3733)
==32455==    by 0x39F960: ngx_http_lua_finalize_fake_request (ngx_http_lua_util.c:3693)
==32455==    by 0x3C56AD: ngx_http_lua_ssl_cert_aborted (ngx_http_lua_ssl_certby.c:422)
==32455==    by 0x1CA1F1: ngx_destroy_pool (ngx_palloc.c:57)
==32455==    by 0x23172B: ngx_http_close_connection (ngx_http_request.c:3731)
==32455==    by 0x22BF36: ngx_http_ssl_handshake_handler (ngx_http_request.c:879)
==32455==    by 0x22BCE0: ngx_http_ssl_handshake (ngx_http_request.c:789)
==32455==    by 0x22AE56: ngx_http_init_connection (ngx_http_request.c:384)
==32455==    by 0x1FDC9F: ngx_event_accept (ngx_event_accept.c:308)
==32455==  Block was alloc'd at
==32455==    at 0x483577F: malloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==32455==    by 0x201E4F: ngx_alloc (ngx_alloc.c:22)
==32455==    by 0x1CA58A: ngx_palloc_large (ngx_palloc.c:220)
==32455==    by 0x1CA375: ngx_palloc (ngx_palloc.c:131)
==32455==    by 0x1CA78E: ngx_pcalloc (ngx_palloc.c:302)
==32455==    by 0x20C272: ngx_thread_task_alloc (ngx_thread_pool.c:219)
==32455==    by 0x412779: ngx_http_lua_io_thread_post_read_task (ngx_http_lua_io.c:248)
==32455==    by 0x411D05: ngx_http_lua_io_file_read_helper (ngx_http_lua_io_module.c:1750)
==32455==    by 0x40F98B: ngx_http_lua_io_file_read (ngx_http_lua_io_module.c:748)
==32455==    by 0x4D01AD5: lj_BC_FUNCC (in /usr/local/lib/libluajit-5.1.so.2.1.0)
==32455==    by 0x39B129: ngx_http_lua_run_thread (ngx_http_lua_util.c:1090)
==32455==    by 0x3C5A20: ngx_http_lua_ssl_cert_by_chunk (ngx_http_lua_ssl_certby.c:533)

After working down the changes the cause appears to be the new luajit2

It appears to be early free'ing of memory, perhaps thread pool memory allocated from the request pool?

[splitice]

Issue went away when i fixed the underlying issue causing the ssl certificate bloock to abort.

Most likely this crash occurs only if the block is aborted. I can't see however how you could fix this.