Fix segmentation fault due to incorrect call to chunk_scan_internal

chunk_scan_internal is called with 2 callback functions, a
filter function and a tuple_found function that
are invoked with the same argument. ts_chunk_set_compressed
and ts_chunk_clear_compressed use chunk_tuple_dropped_filter
but do not pass in the required ChunkStubScanCtx* as argument.
Instead an argument of type int* is passed in. This causes
 a segmentation fault.

Add a new chunk filter function that is compatible with
the tuple_found function used by ts_chunk_clear_compressed_chunk
and ts_chunk_set_compressed_chunk
Fixes #3158

CHANGELOG.md

@@ -10,8 +10,12 @@ accidentally triggering the load of a previous DB version.**
 * #3209 Propagate grants to compressed hypertables
 * #3241 Fix assertion failure in decompress_chunk_plan_create
 * #3250 Fix constraint triggers on hypertables
+* #3251 Fix segmentation fault due to incorrect call to chunk_scan_internal
 * #3252 Fix blocking triggers with transition tables
 
+**Thanks**
+* @yyjdelete for reporting a crash with decompress_chunk and identifying the bug in the code
+
 ## 2.2.1 (2021-05-05)
 
 This maintenance release contains bugfixes since the 2.2.0 release. We

src/chunk.c

@@ -1322,6 +1322,24 @@ chunk_tuple_dropped_filter(TupleInfo *ti, void *arg)
 	return stubctx->is_dropped ? SCAN_EXCLUDE : SCAN_INCLUDE;
 }
 
+/* This is a modified version of chunk_tuple_dropped_filter that does
+ * not use ChunkStubScanCtx as the arg, it just ignores the passed in
+ * argument.
+ * We need a variant as the ScannerCtx assumes that the the filter function
+ * and tuple_found function share the argument.
+ */
+static ScanFilterResult
+chunk_check_ignorearg_dropped_filter(TupleInfo *ti, void *arg)
+{
+	bool isnull;
+	Datum dropped = slot_getattr(ti->slot, Anum_chunk_dropped, &isnull);
+
+	Assert(!isnull);
+	bool is_dropped = DatumGetBool(dropped);
+
+	return is_dropped ? SCAN_EXCLUDE : SCAN_INCLUDE;
+}
+
 static ScanTupleResult
 chunk_tuple_found(TupleInfo *ti, void *arg)
 {
@@ -3128,7 +3146,7 @@ ts_chunk_set_compressed_chunk(Chunk *chunk, int32 compressed_chunk_id)
 	return chunk_scan_internal(CHUNK_ID_INDEX,
 							   scankey,
 							   1,
-							   chunk_tuple_dropped_filter,
+							   chunk_check_ignorearg_dropped_filter,
 							   chunk_set_compressed_id_in_tuple,
 							   &compressed_chunk_id,
 							   0,
@@ -3151,7 +3169,7 @@ ts_chunk_clear_compressed_chunk(Chunk *chunk)
 	return chunk_scan_internal(CHUNK_ID_INDEX,
 							   scankey,
 							   1,
-							   chunk_tuple_dropped_filter,
+							   chunk_check_ignorearg_dropped_filter,
 							   chunk_clear_compressed_status_in_tuple,
 							   &compressed_chunk_id,
 							   0,