From: Guy Harris <guy@alum.mit.edu>
Date: Mon, 6 Aug 2012 22:25:30 +0000 (-0700)
Subject: Check whether libusb_init() succeeds, and give up if it doesn't.
X-Git-Url: https://git.tcpdump.org/libpcap/commitdiff_plain/9364528b46624fd14a86662d54ea550a4f45fe14

Check whether libusb_init() succeeds, and give up if it doesn't.

libusb_init() isn't guaranteed to succeed; it returns a (presumably)
non-zero error on failure.  If it doesn't return 0, just give up - we
presumably don't have a valid libusb_context pointer, which is probably
what's causing crashes when we call libusb_get_device_list() on a system
with no usbfs mounted.

This fixes bug 3554749 in the tracker, and a bunch of upstream bugs.
---

diff --git a/pcap-canusb-linux.c b/pcap-canusb-linux.c
index 5abfe18e..373f0a98 100644
--- a/pcap-canusb-linux.c
+++ b/pcap-canusb-linux.c
@@ -96,8 +96,15 @@ int canusb_platform_finddevs(pcap_if_t **alldevsp, char *err_str)
     unsigned char buf[96];
     int cnt, i;
     
-    libusb_init(&fdctx);
-        
+    if (libusb_init(&fdctx) != 0) {
+        /*
+         * XXX - if this doesn't just mean "no USB file system mounted",
+         * perhaps we should report a real error rather than just
+         * saying "no CANUSB devices".
+         */
+        return 0;
+    } 
+
     cnt = libusb_get_device_list(fdctx,&devs);
 
     for(i=0;i<cnt;i++)