[dm-devel] [PATCH 2/4] multipathd: cli_getprkey(): fix return value

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

By setting (*reply)[19] = '\0', we always truncated a possible
":aptpl" suffix. Fix it, and use the return value of snprintf()
as length.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 multipathd/cli_handlers.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/multipathd/cli_handlers.c b/multipathd/cli_handlers.c
index 9606494..59d44b4 100644
--- a/multipathd/cli_handlers.c
+++ b/multipathd/cli_handlers.c
@@ -1540,7 +1540,7 @@ cli_getprkey(void * v, char ** reply, int * len, void * data)
 	struct multipath * mpp;
 	struct vectors * vecs = (struct vectors *)data;
 	char *mapname = get_keyparam(v, MAP);
-	char *flagstr = "";
+	uint64_t key;
 
 	mapname = convert_dev(mapname, 0);
 	condlog(3, "%s: get persistent reservation key (operator)", mapname);
@@ -1553,17 +1553,16 @@ cli_getprkey(void * v, char ** reply, int * len, void * data)
 	if (!*reply)
 		return 1;
 
-	if (!get_be64(mpp->reservation_key)) {
+	key = get_be64(mpp->reservation_key);
+	if (!key) {
 		sprintf(*reply, "none\n");
-		*len = strlen(*reply) + 1;
+		*len = sizeof("none\n");
 		return 0;
 	}
-	if (mpp->sa_flags & MPATH_F_APTPL_MASK)
-		flagstr = ":aptpl";
-	snprintf(*reply, 26, "0x%" PRIx64 "%s\n",
-		 get_be64(mpp->reservation_key), flagstr);
-	(*reply)[19] = '\0';
-	*len = strlen(*reply) + 1;
+
+	/* This snprintf() can't overflow - PRIx64 needs max 16 chars */
+	*len = snprintf(*reply, 26, "0x%" PRIx64 "%s\n", key,
+			mpp->sa_flags & MPATH_F_APTPL_MASK ? ":aptpl" : "") + 1;
 	return 0;
 }
 
-- 
2.31.1