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ref: 09c9395ff8b23b5c7beb431d0228d5e2129d56d6
parent: 81047afb4bf5e73b7f9a388268124241e06b24bd
author: ISSOtm <[email protected]>
date: Sun Oct 13 11:17:34 EDT 2019 

Fix NULL deref when fetching an unknown symbol in RPN expressions
 was being overwritten with the result, so
was meaningless. Using a temporary instead is better.


--- a/src/link/patch.c
+++ b/src/link/patch.c
@@ -192,11 +192,13 @@
 
 			/* If the symbol is defined elsewhere... */
 			if (symbol->type == SYMTYPE_IMPORT) {
-				symbol = sym_GetSymbol(symbol->name);
-				if (!symbol)
+				struct Symbol const *symbolDefinition =
+						sym_GetSymbol(symbol->name);
+				if (!symbolDefinition)
 					errx(1, "%s(%d): Unknown symbol \"%s\"",
 					     patch->fileName, patch->lineNo,
 					     symbol->name);
+				symbol = symbolDefinition;
 			}
 
 			value = symbol->section->bank;
@@ -250,11 +252,13 @@
 
 			/* If the symbol is defined elsewhere... */
 			if (symbol->type == SYMTYPE_IMPORT) {
-				symbol = sym_GetSymbol(symbol->name);
-				if (!symbol)
+				struct Symbol const *symbolDefinition =
+						sym_GetSymbol(symbol->name);
+				if (!symbolDefinition)
 					errx(1, "%s(%d): Unknown symbol \"%s\"",
 					     patch->fileName, patch->lineNo,
 					     symbol->name);
+				symbol = symbolDefinition;
 			}
 
 			if (!strcmp(symbol->name, "@")) {