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Commita9fdb48

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pg_stat_statements: fetch stmt location/length before it disappears.
When executing a utility statement, we must fetch everythingwe need out of the PlannedStmt data structure before callingstandard_ProcessUtility. In certain cases (possibly only ROLLBACKin extended query protocol), that data structure will get freedduring command execution. The situation is probably often harmlessin production builds, but in debug builds we intentionally overwritethe freed memory with garbage, leading to picking up garbage valuesof statement location and length, typically causing an assertionfailure later in pg_stat_statements. In non-debug builds, ifsomething did go wrong it would likely lead to storing garbagefor the query string.Report and fix by zhaoqigui (with cosmetic adjustments by me).It's an old problem, so back-patch to all supported versions.Discussion:https://postgr.es/m/17663-a344fd0675f92128@postgresql.orgDiscussion:https://postgr.es/m/1667307420050.56657@hundsun.com
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‎contrib/pg_stat_statements/pg_stat_statements.c

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1117,6 +1117,8 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
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DestReceiver*dest,QueryCompletion*qc)
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{
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Node*parsetree=pstmt->utilityStmt;
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intsaved_stmt_location=pstmt->stmt_location;
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intsaved_stmt_len=pstmt->stmt_len;
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/*
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* If it's an EXECUTE statement, we don't track it and don't increment the
@@ -1167,6 +1169,13 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
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}
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PG_END_TRY();
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/*
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* CAUTION: do not access the *pstmt data structure again below here.
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* If it was a ROLLBACK or similar, that data structure may have been
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* freed. We must copy everything we still need into local variables,
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* which we did above.
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*/
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INSTR_TIME_SET_CURRENT(duration);
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INSTR_TIME_SUBTRACT(duration,start);
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@@ -1182,8 +1191,8 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
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pgss_store(queryString,
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0,/* signal that it's a utility stmt */
1185-
pstmt->stmt_location,
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pstmt->stmt_len,
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saved_stmt_location,
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saved_stmt_len,
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PGSS_EXEC,
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INSTR_TIME_GET_MILLISEC(duration),
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rows,

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