From: Dmitry Osipenko <digetx@xxxxxxxxx> commit bf88fef0b6f1488abeca594d377991171c00e52a upstream. The HNP work can be re-scheduled while it's still in-fly. This results in re-initialization of the busy work, resetting the hrtimer's list node of the work and crashing kernel with null dereference within kernel/timer once work's timer is expired. It's very easy to trigger this problem by re-plugging USB cable quickly. Initialize HNP work only once to fix this trouble. Unable to handle kernel NULL pointer dereference at virtual address 00000126) ... PC is at __run_timers.part.0+0x150/0x228 LR is at __next_timer_interrupt+0x51/0x9c ... (__run_timers.part.0) from [<c0187a2b>] (run_timer_softirq+0x2f/0x50) (run_timer_softirq) from [<c01013ad>] (__do_softirq+0xd5/0x2f0) (__do_softirq) from [<c012589b>] (irq_exit+0xab/0xb8) (irq_exit) from [<c0170341>] (handle_domain_irq+0x45/0x60) (handle_domain_irq) from [<c04c4a43>] (gic_handle_irq+0x6b/0x7c) (gic_handle_irq) from [<c0100b65>] (__irq_svc+0x65/0xac) Cc: stable@xxxxxxxxxxxxxxx Acked-by: Peter Chen <peter.chen@xxxxxxxxxx> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> Link: https://lore.kernel.org/r/20210717182134.30262-6-digetx@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/common/usb-otg-fsm.c | 6 +++++- include/linux/usb/otg-fsm.h | 1 + 2 files changed, 6 insertions(+), 1 deletion(-) --- a/drivers/usb/common/usb-otg-fsm.c +++ b/drivers/usb/common/usb-otg-fsm.c @@ -206,7 +206,11 @@ static void otg_start_hnp_polling(struct if (!fsm->host_req_flag) return; - INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work); + if (!fsm->hnp_work_inited) { + INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work); + fsm->hnp_work_inited = true; + } + schedule_delayed_work(&fsm->hnp_polling_work, msecs_to_jiffies(T_HOST_REQ_POLL)); } --- a/include/linux/usb/otg-fsm.h +++ b/include/linux/usb/otg-fsm.h @@ -195,6 +195,7 @@ struct otg_fsm { struct mutex lock; u8 *host_req_flag; struct delayed_work hnp_polling_work; + bool hnp_work_inited; bool state_changed; };
