[PATCH iproute] bridge: catch invalid stp state

[Stephen Hemminger <stephen@networkplumber.org>]

The stp state parsing was putting result in an __u8 which
would mean that check for invalid string was never happening.

Caught by enabling -Wextra:
    CC       mst.o
mst.c: In function ‘mst_set’:
mst.c:217:27: warning: comparison is always false due to limited range of data type [-Wtype-limits]
  217 |                 if (state == -1) {

Fixes: dae3e5de6eac ("bridge: mst: Add get/set support for MST states")

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

---
 bridge/mst.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/bridge/mst.c b/bridge/mst.c
index fccb7fd6..32f64aba 100644
--- a/bridge/mst.c
+++ b/bridge/mst.c
@@ -176,7 +176,7 @@ static int mst_set(int argc, char **argv)
 	char *d = NULL, *m = NULL, *s = NULL, *endptr;
 	struct rtattr *af_spec, *mst, *entry;
 	__u16 msti;
-	__u8 state;
+	int state;
 
 	while (argc > 0) {
 		if (strcmp(*argv, "dev") == 0) {
@@ -212,13 +212,12 @@ static int mst_set(int argc, char **argv)
 	}
 
 	state = strtol(s, &endptr, 10);
-	if (!(*s != '\0' && *endptr == '\0')) {
+	if (!(*s != '\0' && *endptr == '\0'))
 		state = parse_stp_state(s);
-		if (state == -1) {
-			fprintf(stderr,
-				"Error: invalid STP port state\n");
-			return -1;
-		}
+	
+	if (state < 0 || state > UINT8_MAX) {
+		fprintf(stderr, "Error: invalid STP port state\n");
+		return -1;
 	}
 
 	af_spec = addattr_nest(&req.n, sizeof(req), IFLA_AF_SPEC);
-- 
2.45.2