convert: fix leaking config strings

In `read_convert_config()`, we end up reading some string values into
variables. We don't free any potentially-existing old values though,
which will result in a memory leak in case the same key has been defined
multiple times.

Fix those leaks.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

convert.c

@@ -1050,14 +1050,20 @@ static int read_convert_config(const char *var, const char *value,
 	 * The command-line will not be interpolated in any way.
 	 */
 
-	if (!strcmp("smudge", key))
+	if (!strcmp("smudge", key)) {
+		FREE_AND_NULL(drv->smudge);
 		return git_config_string(&drv->smudge, var, value);
+	}
 
-	if (!strcmp("clean", key))
+	if (!strcmp("clean", key)) {
+		FREE_AND_NULL(drv->clean);
 		return git_config_string(&drv->clean, var, value);
+	}
 
-	if (!strcmp("process", key))
+	if (!strcmp("process", key)) {
+		FREE_AND_NULL(drv->process);
 		return git_config_string(&drv->process, var, value);
+	}
 
 	if (!strcmp("required", key)) {
 		drv->required = git_config_bool(var, value);

t/t0021-conversion.sh

@@ -5,6 +5,7 @@ test_description='blob conversion via gitattributes'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-terminal.sh