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Fix use-after-free crash in websocket mutex during connection teardown. Add new swclt_wss_stop() API #143

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Merged
andywolk merged 2 commits into from
Jan 21, 2026
Merged

Fix use-after-free crash in websocket mutex during connection teardown. Add new swclt_wss_stop() API #143

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e1ca286
Fix use-after-free crash in websocket mutex during connection teardown
andywolk Jan 20, 2026
9fff8f3
Simplify adding new swclt_wss_stop() API.
andywolk Jan 21, 2026
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1 change: 1 addition & 0 deletions inc/signalwire-client-c/transport/websocket.h
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,7 @@ SWCLT_DECLARE(ks_status_t) swclt_wss_connect(
uint32_t timeout_ms,
const SSL_CTX *ssl);

SWCLT_DECLARE(void) swclt_wss_stop(swclt_wss_t *wss);
SWCLT_DECLARE(void) swclt_wss_destroy(swclt_wss_t **wss);

SWCLT_DECLARE(ks_status_t) swclt_wss_write(swclt_wss_t *wss, char *data);
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9 changes: 8 additions & 1 deletion src/connection.c
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Expand Up @@ -672,10 +672,17 @@ SWCLT_DECLARE(void) swclt_conn_destroy(swclt_conn_t **conn)
if ((*conn)->blade_connect_rpl) {
BLADE_CONNECT_RPL_DESTROY(&(*conn)->blade_connect_rpl);
}
swclt_wss_destroy(&(*conn)->wss);

/* 1. Stop websocket reader: prevents new jobs from being queued
* 2. Drain thread pool: lets pending jobs finish (they use wss_mutex)
* 3. Destroy websocket: now safe to free the mutex
*/

swclt_wss_stop((*conn)->wss);
if ((*conn)->incoming_frame_pool) {
ks_thread_pool_destroy(&(*conn)->incoming_frame_pool);
}
swclt_wss_destroy(&(*conn)->wss);
ttl_tracker_destroy(&(*conn)->ttl);
ks_hash_destroy(&(*conn)->outstanding_requests);
ks_mutex_destroy(&(*conn)->failed_mutex);
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19 changes: 11 additions & 8 deletions src/transport/websocket.c
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Expand Up @@ -312,19 +312,22 @@ static ks_status_t __connect_socket(swclt_wss_t *ctx)
return status;
}

SWCLT_DECLARE(void) swclt_wss_stop(swclt_wss_t *wss)
{
if (wss && wss->reader_thread) {
ks_log(KS_LOG_DEBUG, "Stopping websocket reader thread");
ks_thread_request_stop(wss->reader_thread);
ks_thread_join(wss->reader_thread);
ks_thread_destroy(&wss->reader_thread);
}
}

SWCLT_DECLARE(void) swclt_wss_destroy(swclt_wss_t **wss)
{
if (wss && *wss) {
ks_pool_t *pool = (*wss)->pool;
ks_log(KS_LOG_INFO, "Shutting down websocket");
if ((*wss)->reader_thread) {
ks_thread_request_stop((*wss)->reader_thread);
}

if ((*wss)->reader_thread) {
ks_thread_join((*wss)->reader_thread);
ks_thread_destroy(&(*wss)->reader_thread);
}
swclt_wss_stop(*wss);
if ((*wss)->wss_mutex) {
ks_mutex_destroy(&(*wss)->wss_mutex);
}
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