From 6e5d01124fd4dd57899ddd9260c76dbb43543aa7 Mon Sep 17 00:00:00 2001 From: Cy Schubert Date: Sat, 2 Apr 2022 20:54:50 -0700 Subject: [PATCH] wpa/hostapd: Fix 100% CPU when USB wlan NIC removed hostapd calls pcap_next(3) to read the next packet off the wlan interface. pcap_next() returns a pointer to the packet header but does not indicate success or failure. Unfortunately this results in an infinite loop (100% CPU) when the wlan device disappears, i.e. when a USB wlan device is manually removed or a USB error results in the device removal. However pcap_next_ex(3) does return success or failure. To resolve this we use pcap_next_ex(), forcing hostapd to exit when the error is encountered. An error message is printed to syslog or stderr when debugging (-d flag) is enabled. Unfortunately wpa_printf() only works when debugging is enabled. PR: 253608 Reported by: Damjan Jovanovic , bz (privately) MFC after: 3 days --- contrib/wpa/src/l2_packet/l2_packet_freebsd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/contrib/wpa/src/l2_packet/l2_packet_freebsd.c b/contrib/wpa/src/l2_packet/l2_packet_freebsd.c index 48e18fffba57..da742f432120 100644 --- a/contrib/wpa/src/l2_packet/l2_packet_freebsd.c +++ b/contrib/wpa/src/l2_packet/l2_packet_freebsd.c @@ -83,7 +83,10 @@ static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx) unsigned char *buf; size_t len; - packet = pcap_next(pcap, &hdr); + if (pcap_next_ex(pcap, &hdr, &packet) == -1) { + wpa_printf(MSG_ERROR, "Error reading packet, has device disappeared?"); + eloop_terminate(); + } if (!l2->rx_callback || !packet || hdr.caplen < sizeof(*ethhdr)) return;