When tearingdown timesync, and not in arche platform, the state platform callback is not initialized. That will trigger the following NULL dereferencing. CallTrace:

? gb_timesync_platform_unlock_bus+0x11/0x20 [greybus] gb_timesync_teardown+0x85/0xc0 [greybus] gb_timesync_svc_remove+0xab/0x190 [greybus] gb_svc_del+0x29/0x110 [greybus] gb_hd_del+0x14/0x20 [greybus] ap_disconnect+0x24/0x60 [gb_es2] usb_unbind_interface+0x7a/0x2c0 __device_release_driver+0x96/0x150 device_release_driver+0x1e/0x30 bus_remove_device+0xe7/0x130 device_del+0x116/0x230 usb_disable_device+0x97/0x1f0 usb_disconnect+0x80/0x260 hub_event+0x5ca/0x10e0 process_one_work+0x126/0x3b0 worker_thread+0x55/0x4c0 ? process_one_work+0x3b0/0x3b0 kthread+0xc4/0xe0 ? kthread_park+0xb0/0xb0 ret_from_fork+0x22/0x30

So, fix that by adding checks before use the callback.

Fixes: 970dc85bd95d ("greybus: timesync: Add timesync core driver") Cc: stable@vger.kernel.org # 4.9.x Signed-off-by: Rui Miguel Silva rmfrfs@gmail.com --- Greg, This patch does not contain the "commit <sha> upstream" snippet since you already removed the timesync code from the -next tree, even though it is still in 4.10-rc. However this will affect the greybus users of 4.9.x. If you meanwhile pull that remove to rc, this patch is only necessary in stable 4.9.x.

v1->v2: - add Fixes tag to changelog Johan Hovold: - for symmetry with the lock, adjust the unlock_bus function accordantly.

drivers/staging/greybus/timesync_platform.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/drivers/staging/greybus/timesync_platform.c b/drivers/staging/greybus/timesync_platform.c index 113f3d6c4b3a..27f75b17679b 100644 --- a/drivers/staging/greybus/timesync_platform.c +++ b/drivers/staging/greybus/timesync_platform.c @@ -45,12 +45,18 @@ u32 gb_timesync_platform_get_clock_rate(void)

int gb_timesync_platform_lock_bus(struct gb_timesync_svc *pdata) { + if (!arche_platform_change_state_cb) + return 0; + return arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_TIME_SYNC, pdata); }

void gb_timesync_platform_unlock_bus(void) { + if (!arche_platform_change_state_cb) + return; + arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_ACTIVE, NULL); }