linux-kernel - Re: [PATCH] add chan->cl check in mbox_chan_received

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Date:   Wed, 16 Dec 2020 08:52:56 +0800
From:   Orson Zhai <orsonzhai@...il.com>
To:     Haidong Yao <yaohaidong369@...il.com>
Cc:     jassisinghbrar@...il.com, natechancellor@...il.com,
        ndesaulniers@...gle.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        clang-built-linux@...glegroups.com,
        Lyra Zhang <zhang.lyra@...il.com>,
        Haidong Yao <haidong.yao@...soc.com>
Subject: Re: [PATCH] add chan->cl check in mbox_chan_received_data()

On Tue, Dec 15, 2020 at 4:48 PM Haidong Yao <yaohaidong369@...il.com> wrote:
>
> From: Haidong Yao <haidong.yao@...soc.com>
>
> mailbox outbox irq is coming, but mbox_request_channel
> is not be registered, so cl->rx_callback is NULL.

Both "chan->cl" and "chan->cl->rx_callback" should be checked for being NULL.


>
> panic log:
> [    9.852090]c0  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
> [    9.954634]c0  pstate: 60400089 (nZCv daIf +PAN -UAO)
> [    9.954651]c0  pc : mbox_chan_received_data+0x1c/0x88
> [    9.954666]c0  lr : sprd_mbox_outbox_isr+0x1d0/0x204 [sprd_mailbox]
> [    9.967439]c0  sp : ffffffc010003e10
> [    9.967443]c0  x29: ffffffc010003e20 x28: ffffffc011c2f6c0-
> [    9.984918]c0  x27: ffffffc010e92e08 x26: 0000000000000001-
> [   10.140344]c0  x25: 0000000000000378 x24: ffffff80f4064130-
> [   10.145880]c0  x23: 0000000000000001 x22: ffffffc0091072c7-
> [   10.151418]c0  x21: ffffffc009107212 x20: 0000000000000005-
> [   10.156957]c0  x19: ffffff80f4064080 x18: ffffffc010005038-
> [   10.162494]c0  x17: 0000000000000000 x16: ffffffc010e6f844-
> [   10.168033]c0  x15: ffffffc0117abac7 x14: 000000000000003f-
> [   10.173571]c0  x13: ffff0000ffffff00 x12: ffff0a01ffffff10-
> [   10.179110]c0  x11: 0000000000000001 x10: 00000000ffffffff-
> [   10.184649]c0  x9 : ffffff80f40644a8 x8 : c366877097809900-
> [   10.190187]c0  x7 : 207273695f786f62 x6 : ffffffc011d62231-
> [   10.195726]c0  x5 : 0000000000000034 x4 : 000000000000000c-
> [   10.201265]c0  x3 : ffffffc010e9842c x2 : 0000000000000001-
> [   10.206803]c0  x1 : ffffffc010003e40 x0 : 0000000000000000-
> [   10.212343]c0  Call trace:
> [   10.215029]c0   mbox_chan_received_data+0x1c/0x88
> [   10.219705]c0   sprd_mbox_outbox_isr+0x1d0/0x204 [sprd_mailbox]
> [   10.225590]c0   __handle_irq_event_percpu+0x164/0x358
> [   10.230604]c0   handle_irq_event+0x60/0xd8
> [   10.234675]c0   handle_fasteoi_irq+0x128/0x32c
> [   10.239086]c0   __handle_domain_irq+0xa0/0x100
> [   10.243502]c0   efi_header_end+0xb8/0x15c
> [   10.247478]c0   el1_irq+0x104/0x200
> [   10.250945]c0   cpuidle_enter_state+0x158/0x2d8
> [   10.255440]c0   cpuidle_enter+0x38/0x50
> [   10.259253]c0   do_idle.llvm.10091284334483161164+0x1a4/0x294
> [   10.264963]c0   cpu_startup_entry+0x24/0x28
> [   10.269120]c0   kernel_init+0x0/0x29c
> [   10.272752]c0   start_kernel+0x0/0x418
> [   10.276468]c0   start_kernel+0x3a0/0x418
> [   10.280371]c0  Code: f90013f3 910043fd aa0003e9 f9400800 (f9401008)-
> [   10.286684]c0  ---[ end trace b868997a960c667a ]---
>
> Signed-off-by: Haidong Yao <haidong.yao@...soc.com>
> ---
>  drivers/mailbox/mailbox.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> index 3e7d4b20ab34..58697298a95f 100644
> --- a/drivers/mailbox/mailbox.c
> +++ b/drivers/mailbox/mailbox.c
> @@ -152,7 +152,7 @@ static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
>  void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
>  {
>         /* No buffering the received data */
> -       if (chan->cl->rx_callback)
> +       if (chan->cl && chan->cl->rx_callback)
>                 chan->cl->rx_callback(chan->cl, mssg);
>  }
>  EXPORT_SYMBOL_GPL(mbox_chan_received_data);

For the code changes,
Acked-by: Orson Zhai <orsonzhai@...il.com>

> --
> 2.28.0
>