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From:   Szymon Janc <szymon.janc@codecoup.pl>
To:     linux-bluetooth@vger.kernel.org
Cc:     Szymon Janc <szymon.janc@codecoup.pl>
Subject: [PATCH] shared/gatt: Fix NULL pointer dereference
Date:   Tue, 31 Mar 2020 12:45:32 +0200
Message-Id: <20200331104532.365961-1-szymon.janc@codecoup.pl>
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Sender: linux-bluetooth-owner@vger.kernel.org
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bluetoothd[363094]: src/device.c:device_connect_le() Connection attempt to: 00:AA:01:00:00:23

Program received signal SIGSEGV, Segmentation fault.
write_complete_cb (attr=0x55555580aa30, err=-110, user_data=0x55555585f7c0) at src/shared/gatt-server.c:793
793             util_debug(server->debug_callback, server->debug_data,
(gdb) bt
 #0  write_complete_cb (attr=0x55555580aa30, err=-110, user_data=0x55555585f7c0) at src/shared/gatt-server.c:793
 #1  0x00005555556a5852 in pending_write_result (p=0x555555866030, err=<optimized out>) at src/shared/gatt-db.c:162
 #2  0x00005555556a5ac7 in write_timeout (user_data=0x555555866030) at src/shared/gatt-db.c:1879
 #3  0x00005555556a9b15 in timeout_callback (user_data=user_data@entry=0x555555864b20) at src/shared/timeout-glib.c:34
 #4  0x00007ffff7e1f081 in g_timeout_dispatch (source=source@entry=0x555555864f00, callback=0x5555556a9b00 <timeout_callback>, user_data=0x555555864b20) at ../glib/gmain.c:4705
 #5  0x00007ffff7e1e570 in g_main_dispatch (context=0x5555557d9630) at ../glib/gmain.c:3216
 #6  g_main_context_dispatch (context=context@entry=0x5555557d9630) at ../glib/gmain.c:3881
 #7  0x00007ffff7e1e900 in g_main_context_iterate (context=0x5555557d9630, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:3954
 #8  0x00007ffff7e1ebf3 in g_main_loop_run (loop=0x5555557d75d0) at ../glib/gmain.c:4148
 #9  0x00005555556a9dbd in mainloop_run () at src/shared/mainloop-glib.c:79
 #10 0x00005555556aa36a in mainloop_run_with_signal (func=<optimized out>, user_data=0x0) at src/shared/mainloop-notify.c:201
 #11 0x00005555555bb9e3 in main (argc=<optimized out>, argv=<optimized out>) at src/main.c:770
---
 src/shared/gatt-server.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c
index 7e5d652e4..4e07398d2 100644
--- a/src/shared/gatt-server.c
+++ b/src/shared/gatt-server.c
@@ -790,14 +790,14 @@ static void write_complete_cb(struct gatt_db_attribute *attr, int err,
 	struct bt_gatt_server *server = op->server;
 	uint16_t handle;
 
-	util_debug(server->debug_callback, server->debug_data,
-				"Write Complete: err %d", err);
-
 	if (!server || op->opcode == BT_ATT_OP_WRITE_CMD) {
 		async_write_op_destroy(op);
 		return;
 	}
 
+	util_debug(server->debug_callback, server->debug_data,
+						"Write Complete: err %d", err);
+
 	handle = gatt_db_attribute_get_handle(attr);
 
 	if (err)
@@ -914,14 +914,14 @@ static void read_complete_cb(struct gatt_db_attribute *attr, int err,
 	uint16_t mtu;
 	uint16_t handle;
 
-	util_debug(server->debug_callback, server->debug_data,
-				"Read Complete: err %d", err);
-
 	if (!server) {
 		async_read_op_destroy(op);
 		return;
 	}
 
+	util_debug(server->debug_callback, server->debug_data,
+				"Read Complete: err %d", err);
+
 	mtu = bt_att_get_mtu(server->att);
 	handle = gatt_db_attribute_get_handle(attr);
 
-- 
2.25.1