lib: fix hci_strtolm crash

|str| can be NULL in the case of reading lm value. Calling strcasestr
could lead to a crash.

Reviewed-by: Archie Pusaka <apusaka@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/hci.c b/lib/hci.c
index 5141f20ac..5228c2ad2 100644
--- a/lib/hci.c
+++ b/lib/hci.c
@@ -323,7 +323,7 @@ int hci_strtolm(char *str, unsigned int *val)
 	int ret = hci_str2bit(link_mode_map, str, val);
 
 	/* Deprecated name. Kept for compatibility. */
-	if (strcasestr(str, "MASTER")) {
+	if (!!str && strcasestr(str, "MASTER")) {
 		ret = 1;
 		*val |= HCI_LM_MASTER;
 	}