core/load-fragment: fix (potential) bad memory access

strncmp() could be used with size bigger then the size of the string,
because MAX was used instead of MIN.

If failing, print just the offending mount flag.

1 files changed, 12 insertions, 5 deletions

diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index 01f94844a6..6933e1a21e 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -1101,15 +1101,22 @@ int config_parse_exec_mount_flags(
         assert(rvalue);
         assert(data);
 
-        FOREACH_WORD_QUOTED(w, l, rvalue, state) {
-                if (strncmp(w, "shared", MAX(l, 6U)) == 0)
+        FOREACH_WORD_SEPARATOR(w, l, rvalue, ", ", state) {
+                char _cleanup_free_ *t;
+
+                t = strndup(w, l);
+                if (!t)
+                        return -ENOMEM;
+
+                if (streq(t, "shared"))
                         flags |= MS_SHARED;
-                else if (strncmp(w, "slave", MAX(l, 5U)) == 0)
+                else if (streq(t, "slave"))
                         flags |= MS_SLAVE;
-                else if (strncmp(w, "private", MAX(l, 7U)) == 0)
+                else if (streq(w, "private"))
                         flags |= MS_PRIVATE;
                 else {
-                        log_error("[%s:%u] Failed to parse mount flags, ignoring: %s", filename, line, rvalue);
+                        log_error("[%s:%u] Failed to parse mount flag %s, ignoring: %s",
+                                  filename, line, t, rvalue);
                         return 0;
                 }
         }