Fix peer connect crash#8889
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rustyrussell merged 2 commits intoElementsProject:masterfrom Feb 11, 2026
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``` lightningd-2 2026-02-09T00:41:35.196Z TRACE lightningd: Plugin peer_connected_logger_a.py returned from peer_connected hook call lightningd-2 2026-02-09T00:41:35.196Z TRACE lightningd: Calling peer_connected hook of plugin peer_connected_logger_b.py lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: FATAL SIGNAL 11 (version v25.12-257-g2a5fbd1-modded) lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: common/daemon.c:46 (send_backtrace) 0x5b2abd7f29bd lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: common/daemon.c:83 (crashdump) 0x5b2abd7f2a0c lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0 ((null)) 0x75950d84532f lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/peer_control.c:1333 (peer_connected_serialize) 0x5b2abd79c964 lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/plugin_hook.c:359 (plugin_hook_call_next) 0x5b2abd7ae14a lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/plugin_hook.c:299 (plugin_hook_callback) 0x5b2abd7ae38f lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/plugin.c:701 (plugin_response_handle) 0x5b2abd7a7e28 lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/plugin.c:790 (plugin_read_json) 0x5b2abd7ace9c lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ccan/ccan/io/io.c:60 (next_plan) 0x5b2abd81dada lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ccan/ccan/io/io.c:422 (do_plan) 0x5b2abd81def6 lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ccan/ccan/io/io.c:439 (io_ready) 0x5b2abd81dfb3 lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ccan/ccan/io/poll.c:470 (io_loop) 0x5b2abd81f0db lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/io_loop_with_timers.c:22 (io_loop_with_timers) 0x5b2abd77c13b lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: lightningd/lightningd.c:1495 (main) 0x5b2abd781c6a lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ../sysdeps/nptl/libc_start_call_main.h:58 (__libc_start_call_main) 0x75950d82a1c9 lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: ../csu/libc-start.c:360 (__libc_start_main_impl) 0x75950d82a28a lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0x5b2abd752964 lightningd-2 2026-02-09T00:41:35.293Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0xffffffffffffffff ``` Signed-off-by: Rusty Russell <[email protected]>
It's always true for the first hook invocation, but if there is more than one plugin, it could vanish between the two! In the default configuration, this can't happen. This bug has been around since v23.02. Note: we always tell all the plugins about the peer, even if it's already gone. Signed-off-by: Rusty Russell <[email protected]> Changelog-Fixed: lightningd: possible crash when peers disconnected if there was more than one plugin servicing the `peer_connected` hook. Reported-by: https://github.com/santyr Fixes: ElementsProject#8858
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Fixes: #8858
Can only happen with an additional plugin (e.g. clboss) which listens to the peer_connected hook.