Add CodeQL check to detect cause of issue openzfs#12014

Signed-off-by: Richard Yao <[email protected]>

Author: ryao

.github/codeql-cpp.yml

@@ -2,3 +2,4 @@ name: "Custom CodeQL Analysis"
 
 queries:
   - uses: ./.github/codeql/custom-queries/cpp/deprecatedFunctionUsage.ql
+  - uses: ./.github/codeql/custom-queries/cpp/dslDatasetHoldReleMismatch.ql

.github/codeql/custom-queries/cpp/dslDatasetHoldReleMismatch.ql

@@ -0,0 +1,34 @@
+/**
+ * @name Detect mismatched dsl_dataset_hold/_rele pairs
+ * @description Flags instances of issue #12014 where
+ *   - a dataset held with dsl_dataset_hold_obj() ends up in dsl_dataset_rele_flags(), or
+ *   - a dataset held with dsl_dataset_hold_obj_flags() ends up in dsl_dataset_rele().
+ * @kind problem
+ * @severity error
+ * @tags correctness
+ * @id cpp/dslDatasetHoldReleMismatch
+ */
+
+import cpp
+
+from Variable ds, Call holdCall, Call releCall, string message
+where
+    ds.getType().toString() = "dsl_dataset_t *" and
+    holdCall.getASuccessor*() = releCall and
+    (
+        (holdCall.getTarget().getName() = "dsl_dataset_hold_obj_flags" and
+         holdCall.getArgument(4).(AddressOfExpr).getOperand().(VariableAccess).getTarget() = ds and
+         releCall.getTarget().getName() = "dsl_dataset_rele" and
+         releCall.getArgument(0).(VariableAccess).getTarget() = ds and
+         message = "Held with dsl_dataset_hold_obj_flags but released with dsl_dataset_rele")
+        or
+        (holdCall.getTarget().getName() = "dsl_dataset_hold_obj" and
+         holdCall.getArgument(3).(AddressOfExpr).getOperand().(VariableAccess).getTarget() = ds and
+         releCall.getTarget().getName() = "dsl_dataset_rele_flags" and
+         releCall.getArgument(0).(VariableAccess).getTarget() = ds and
+         message = "Held with dsl_dataset_hold_obj but released with dsl_dataset_rele_flags")
+    )
+select releCall,
+       "Mismatched release: held with $@ but released with " + releCall.getTarget().getName() + " for dataset $@",
+       holdCall, holdCall.getTarget().getName(),
+       ds, ds.toString()