FIX: crash on Bionic libc if CloseProxmark is called twice. (#672)

In Android O and later, if an invalid pthread_t is passed to pthread_join,
it calls fatal().

https://github.com/aosp-mirror/platform_bionic/blob/ed16b344e75f422fb36fbfd91fb30de339475880/libc/bionic/pthread_internal.cpp#L116-L128

This patch addresses it by:

1. Always memset(0) on USB_communications_thread at the end of
   CloseProxmark.

2. On Bionic, only call pthread_join on USB_communications_thread if it is
   not equal to 0.

diff --git a/client/comms.c b/client/comms.c
index 2030f8f3ea6010946bbc990aa1dcbc805c9bbbfd..86dca3ed425022276c4c976de85ec15bd63b4f79 100644 (file)
--- a/client/comms.c
+++ b/client/comms.c
@@ -333,7 +333,20 @@ bool OpenProxmark(void *port, bool wait_for_port, int timeout, bool flash_mode)
 
 void CloseProxmark(void) {
        conn.run = false;
+
+#ifdef __BIONIC__
+       // In Android O and later, if an invalid pthread_t is passed to pthread_join, it calls fatal().
+       // https://github.com/aosp-mirror/platform_bionic/blob/ed16b344e75f422fb36fbfd91fb30de339475880/libc/bionic/pthread_internal.cpp#L116-L128
+       //
+       // In Bionic libc, pthread_t is an integer.
+
+       if (USB_communication_thread != 0) {
+               pthread_join(USB_communication_thread, NULL);
+       }
+#else
+       // pthread_t is a struct on other libc, treat as an opaque memory reference
        pthread_join(USB_communication_thread, NULL);
+#endif
 
        if (sp) {
                uart_close(sp);
@@ -351,6 +364,7 @@ void CloseProxmark(void) {
        // Clean up our state
        sp = NULL;
        serial_port_name = NULL;
+       memset(&USB_communication_thread, 0, sizeof(pthread_t));
 }