liveupdate: reject LIVEUPDATE_IOCTL_CREATE_SESSION with invalid name length

A session name must not be an empty string, and must not exceed the
maximum size define in the uapi header, including null termination.

Fixes: 0153094 ("liveupdate: luo_session: add sessions support")
Cc: stable@vger.kernel.org

Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://lore.kernel.org/r/20260429212221.814107-2-luca.boccassi@gmail.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Author: bluca

kernel/liveupdate/luo_session.c

@@ -382,9 +382,13 @@ static int luo_session_getfile(struct luo_session *session, struct file **filep)
 
 int luo_session_create(const char *name, struct file **filep)
 {
+	size_t len = strnlen(name, LIVEUPDATE_SESSION_NAME_LENGTH);
 	struct luo_session *session;
 	int err;
 
+	if (len == 0 || len > LIVEUPDATE_SESSION_NAME_LENGTH - 1)
+		return -EINVAL;
+
 	session = luo_session_alloc(name);
 	if (IS_ERR(session))
 		return PTR_ERR(session);