HAL_ChibiOS: protect chEvtSignal from null waiter

This fixes #29370
ArduPilot · Feb 25, 2025 · cb67ae5 · cb67ae5
1 parent 0fb627f
commit cb67ae5
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Showing 2 changed files with 12 additions and 5 deletions.
diff --git a/libraries/AP_HAL_ChibiOS/RCOutput.cpp b/libraries/AP_HAL_ChibiOS/RCOutput.cpp
@@ -1842,10 +1842,11 @@ __RAMFUNC__ void RCOutput::dma_unlock(virtual_timer_t* vt, void *p)
     pwm_group *group = (pwm_group *)p;
 
     group->dshot_state = DshotState::IDLE;
-    if (group->dshot_waiter != nullptr) {
+    auto *waiter = group->dshot_waiter;
+    if (waiter != nullptr) {
         // tell the waiting process we've done the DMA. Note that
         // dshot_waiter can be null if we have cancelled the send
-        chEvtSignalI(group->dshot_waiter, group->dshot_event_mask);
+        chEvtSignalI(waiter, group->dshot_event_mask);
     }
     chSysUnlockFromISR();
 }

diff --git a/libraries/AP_HAL_ChibiOS/RCOutput_bdshot.cpp b/libraries/AP_HAL_ChibiOS/RCOutput_bdshot.cpp
@@ -515,8 +515,11 @@ __RAMFUNC__ void RCOutput::bdshot_finish_dshot_gcr_transaction(virtual_timer_t*
     // although it should be possible to start the next DMAR transaction concurrently with receiving 
     // telemetry, in practice it seems to interfere with the DMA engine
     if (group->shared_up_dma && group->bdshot.enabled) {
-        // next dshot pulse can go out now
-        chEvtSignalI(group->dshot_waiter, DSHOT_CASCADE);
+        auto *waiter = group->dshot_waiter;
+        if (waiter != nullptr) {
+            // next dshot pulse can go out now
+            chEvtSignalI(waiter, DSHOT_CASCADE);
+        }
     }
 #endif
     // if using input capture DMA and sharing the UP and CH channels then clean up
@@ -541,7 +544,10 @@ __RAMFUNC__ void RCOutput::bdshot_finish_dshot_gcr_transaction(virtual_timer_t*
     }
 
     // tell the waiting process we've done the DMA
-    chEvtSignalI(group->dshot_waiter, group->dshot_event_mask);
+    auto *waiter = group->dshot_waiter;
+    if (waiter != nullptr) {
+        chEvtSignalI(waiter, group->dshot_event_mask);
+    }
 #ifdef HAL_GPIO_LINE_GPIO56
     TOGGLE_PIN_DEBUG(56);
 #endif