From: Marek Lindner <mareklindner@neomailbox.ch>
Date: Wed, 29 Apr 2020 12:09:44 +0200
Subject: batctl: fix endianness when reading radiotap header

All radiotap header fields are specified in little endian byte-order.
Header length conversion is necessary on some platforms.

Fixes: c6fcdb6dc9a9 ("batctl: add radiotap wifi packet decapsulation support")
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

Origin: upstream, https://git.open-mesh.org/batctl.git/commit/440ae55a6ef96eb73ee628f9237915cf9fb26dee

diff --git a/tcpdump.c b/tcpdump.c
index dc4ccd37c3ddf8650cb79737defd923fe9f33c64..c41500e21eda0abc1f024a3265c23fc3a4802d17 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -29,6 +29,7 @@
 #include <time.h>
 #include <sys/time.h>
 #include <arpa/inet.h>
+#include <endian.h>
 #include <net/if.h>
 #include <net/if_arp.h>
 #include <netinet/in.h>
@@ -1048,10 +1049,10 @@ static int monitor_header_length(unsigned char *packet_buff, ssize_t buff_len, i
 			return -1;
 
 		radiotap_hdr = (struct radiotap_header*)packet_buff;
-		if (buff_len <= radiotap_hdr->it_len)
+		if (buff_len <= le16toh(radiotap_hdr->it_len))
 			return -1;
 		else
-			return radiotap_hdr->it_len;
+			return le16toh(radiotap_hdr->it_len);
 	}
 
 	return -1;