On Mon, Jan 23, 2017 at 02:22:44PM +0000, Rui Miguel Silva wrote:
> 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.
>
> Cc: <[email protected]> # 4.9.x
> Signed-off-by: Rui Miguel Silva <[email protected]>
> ---
> Greg,
> This patch does not contain the "commit <sha> upstream" snippet since you
> already removed the timesync code from the -next tree. So, It would never get
> there. However this will affect the greybus users of 4.9.x.
This code is still in Linus tree and 4.10-rc so this is just a normal
fix even if this is no longer an issue in -next.
> drivers/staging/greybus/timesync_platform.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/greybus/timesync_platform.c
> b/drivers/staging/greybus/timesync_platform.c
> index 113f3d6c4b3a..7d3ccc2bc98c 100644
> --- a/drivers/staging/greybus/timesync_platform.c
> +++ b/drivers/staging/greybus/timesync_platform.c
> @@ -45,13 +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)
> {
> - arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_ACTIVE, NULL);
> + if (arche_platform_change_state_cb)
> + arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_ACTIVE,
> + NULL);
I'd use the same pattern here:
if (!arche_platform_change_state_cb)
return;
arche_platform_change_state_cb(ARCHE_PLATFORM_STATE_ACTIVE, NULL);
Thanks,
Johan
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