strvec_join: free result on error and actually use separator char

plugins/sudoers/regress/unescape/check_unesc.c

@@ -86,14 +86,15 @@ test_strlcpy_unescape(int *ntests_out, int *errors_out)
 }
 
 static void
-test_strvec_join(int *ntests_out, int *errors_out)
+test_strvec_join(char sep, int *ntests_out, int *errors_out)
 {
     int ntests = *ntests_out;
     int errors = *errors_out;
     char buf[64*1024 + 1], expected[64*1024 + 3];
     char *argv[3], *result;
 
     /* Test joining an argument vector while unescaping. */
+    /* Simulate: sudoedit -s '\' `perl -e 'print "A" x 65536'` */
     memset(buf, 'A', sizeof(buf));
     buf[sizeof(buf) - 1] = '\0';
     argv[0] = "\\";
@@ -102,11 +103,11 @@ test_strvec_join(int *ntests_out, int *errors_out)
 
     memset(expected, 'A', sizeof(expected));
     expected[0] = '\\';
-    expected[1] = ' ';
+    expected[1] = sep;
     expected[sizeof(expected) - 1] = '\0';
 
     ntests++;
-    result = strvec_join(argv, ' ', strlcpy_unescape);
+    result = strvec_join(argv, sep, strlcpy_unescape);
     if (result == NULL) {
 	sudo_warnx("%d: failed to join argument vector", ntests);
 	errors++;
@@ -132,7 +133,8 @@ main(int argc, char *argv[])
     test_strlcpy_unescape(&ntests, &errors);
 
     /* strvec_join test */
-    test_strvec_join(&ntests, &errors);
+    test_strvec_join(' ', &ntests, &errors);
+    test_strvec_join('\n', &ntests, &errors);
 
     printf("%s: %d tests run, %d errors, %d%% success rate\n", getprogname(),
 	ntests, errors, (ntests - errors) * 100 / ntests);

plugins/sudoers/strvec_join.c

@@ -29,8 +29,12 @@
 
 #include "sudoers.h"
 
+/*
+ * Join a NULL-terminated array of strings using the specified separator
+ * character.  The copy function must have strlcpy-like semantics.
+ */
 char *
-strvec_join(char *const argv[], char ch, size_t (*cpy)(char *, const char *, size_t))
+strvec_join(char *const argv[], char sep, size_t (*cpy)(char *, const char *, size_t))
 {
     char *dst, *result = NULL;
     char *const *av;
@@ -48,11 +52,12 @@ strvec_join(char *const argv[], char ch, size_t (*cpy)(char *, const char *, siz
 	n = cpy(dst, *av, size);
 	if (n >= size) {
 	    sudo_warnx(U_("internal error, %s overflow"), __func__);
+	    free(result);
 	    debug_return_ptr(NULL);
 	}
 	dst += n;
 	size -= n;
-	*dst++ = ' ';
+	*dst++ = sep;
 	size--;
     }
     *--dst = '\0';

plugins/sudoers/sudoers.h

@@ -459,6 +459,6 @@ void rcstr_delref(const char *s);
 size_t strlcpy_unescape(char *dst, const char *src, size_t size);
 
 /* strvec_join.c */
-char *strvec_join(char *const argv[], char ch, size_t (*cpy)(char *, const char *, size_t));
+char *strvec_join(char *const argv[], char sep, size_t (*cpy)(char *, const char *, size_t));
 
 #endif /* SUDOERS_SUDOERS_H */