[PATCH v2] shared/gatt-client: Fix crash on ext prop read failure

[Szymon Janc <szymon.janc@codecoup.pl>]

Program received signal SIGSEGV, Segmentation fault.

Program received signal SIGSEGV, Segmentation fault.
ext_prop_read_cb (success=false, att_ecode=0 '\000', value=0x0,
    length=0, user_data=0x72ad30) at src/shared/gatt-client.c:711
711     src/shared/gatt-client.c: No such file or directory.
(gdb) bt
0  ext_prop_read_cb (success=false, att_ecode=0 '\000', value=0x0,
                     length=0, user_data=0x72ad30)
   at src/shared/gatt-client.c:711
1  0x000000000049b8cc in disc_att_send_op (data=0x7199b0)
   at src/shared/att.c:547
2  0x000000000049cb44 in disconnect_cb (io=<optimized out>,
                       user_data=0x716070) at src/shared/att.c:580
3  0x00000000004a6405 in watch_callback (channel=<optimized out>,
                      cond=<optimized out>, user_data=<optimized out>)
   at src/shared/io-glib.c:170
4  0x00007ffff78c704a in g_main_context_dispatch ()
   from /lib/x86_64-linux-gnu/libglib-2.0.so.0
5  0x00007ffff78c73f0 in ?? ()
   from /lib/x86_64-linux-gnu/libglib-2.0.so.0
6  0x00007ffff78c7712 in g_main_loop_run ()
   from /lib/x86_64-linux-gnu/libglib-2.0.so.0
7  0x000000000040c620 in main (argc=1, argv=0x7fffffffe5a8)
   at src/main.c:781
---
 src/shared/gatt-client.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/shared/gatt-client.c b/src/shared/gatt-client.c
index 2e153db5c..3c2aa293b 100644
--- a/src/shared/gatt-client.c
+++ b/src/shared/gatt-client.c
@@ -708,6 +708,9 @@ static void ext_prop_read_cb(bool success, uint8_t att_ecode,
 	bool discovering;
 	struct gatt_db_attribute *desc_attr = NULL;
 
+	if (!success)
+		goto done;
+
 	util_debug(client->debug_callback, client->debug_data,
 				"Ext. prop value: 0x%04x", (uint16_t)value[0]);
 
-- 
2.17.1