WebRTC: Fix race condition in RTC nack timer callbacks. v7.0.79 (#4474)

See [WebRTC: Fix race condition in RTC publish timer
callbacks.](421ab6c3fb)
v7.0.76 (https://github.com/ossrs/srs/pull/4470)

trunk/doc/CHANGELOG.md

@@ -7,6 +7,7 @@ The changelog for SRS.
 <a name="v7-changes"></a>
 
 ## SRS 7.0 Changelog
+* v7.0, 2025-09-05, Merge [#4474](https://github.com/ossrs/srs/pull/4474): WebRTC: Fix race condition in RTC nack timer callbacks. v7.0.79 (#4474)
 * v7.0, 2025-09-04, Merge [#4467](https://github.com/ossrs/srs/pull/4467): WebRTC: Fix NACK recovered packets not being added to receive queue. v7.0.78 (#4467)
 * v7.0, 2025-09-03, Merge [#4469](https://github.com/ossrs/srs/pull/4469): Upgrade HTTP parser from http-parser to llhttp. v7.0.77 (#4469)
 * v7.0, 2025-09-03, Merge [#4470](https://github.com/ossrs/srs/pull/4470): RTX: Fix race condition for timer. v7.0.76 (#4470)

trunk/src/app/srs_app_rtc_conn.cpp

@@ -1745,18 +1745,29 @@ void SrsRtcPublishStream::update_send_report_time(uint32_t ssrc, const SrsNtp &n
 
 SrsRtcConnectionNackTimer::SrsRtcConnectionNackTimer(SrsRtcConnection *p) : p_(p)
 {
+    lock_ = srs_mutex_new();
     _srs_shared_timer->timer20ms()->subscribe(this);
 }
 
 SrsRtcConnectionNackTimer::~SrsRtcConnectionNackTimer()
 {
-    _srs_shared_timer->timer20ms()->unsubscribe(this);
+    if (true) {
+        SrsLocker(lock_);
+        _srs_shared_timer->timer20ms()->unsubscribe(this);
+    }
+    srs_mutex_destroy(lock_);
 }
 
 srs_error_t SrsRtcConnectionNackTimer::on_timer(srs_utime_t interval)
 {
     srs_error_t err = srs_success;
 
+    // This is a very heavy function, and it may potentially cause a coroutine switch.
+    // Therefore, during this function, the 'this' pointer might become invalid because
+    // the object could be freed by another thread. As a result, we must lock the object
+    // to prevent it from being freed.
+    SrsLocker(lock_);
+
     if (!p_->nack_enabled_) {
         return err;
     }

trunk/src/app/srs_app_rtc_conn.hpp

@@ -454,6 +454,7 @@ class SrsRtcConnectionNackTimer : public ISrsFastTimer
 {
 private:
     SrsRtcConnection *p_;
+    srs_mutex_t lock_;
 
 public:
     SrsRtcConnectionNackTimer(SrsRtcConnection *p);

trunk/src/core/srs_core_version7.hpp

@@ -9,6 +9,6 @@
 
 #define VERSION_MAJOR 7
 #define VERSION_MINOR 0
-#define VERSION_REVISION 78
+#define VERSION_REVISION 79
 
 #endif