From: Luca Boccassi <luca.boccassi@microsoft.com>
Date: Thu, 1 Apr 2021 22:18:29 +0100
Subject: LoadCredentials: do not assert on invalid syntax

LoadCredentials=foo causes an assertion to be triggered, as we
are not checking that the rvalue's right hand side part is non-empty
before using it in unit_full_printf.

Fixes #19178

# printf [Service]nLoadCredential=passwd.hashed-password.rootn > hello.service
# systemd-analyze verify ./hello.service
...
Assertion 'format' failed at src/core/unit-printf.c:232, function unit_full_printf(). Aborting.
Aborted (core dumped)

(cherry picked from commit f7a6f1226e800f7695c2073675523062ea697aa4)
---
 src/core/load-fragment.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index 4964249..5b66fb1 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -4569,7 +4569,7 @@ int config_parse_load_credential(
         r = extract_first_word(&p, &word, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
         if (r == -ENOMEM)
                 return log_oom();
-        if (r <= 0) {
+        if (r <= 0 || isempty(p)) {
                 log_syntax(unit, LOG_WARNING, filename, line, r, "Invalid syntax, ignoring: %s", rvalue);
                 return 0;
         }