Re: [PATCH v2] Bluetooth: hci_qca: Fix driver shutdown on closed serdev

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 29/12/2022 11:28, Krzysztof Kozlowski wrote:
> The driver shutdown callback (which sends EDL_SOC_RESET to the device
> over serdev) should not be invoked when HCI device is not open (e.g. if
> hci_dev_open_sync() failed), because the serdev and its TTY are not open
> either.  Also skip this step if device is powered off
> (qca_power_shutdown()).
> 
> The shutdown callback causes use-after-free during system reboot with
> Qualcomm Atheros Bluetooth:
> 
>   Unable to handle kernel paging request at virtual address 0072662f67726fd7
>   ...
>   CPU: 6 PID: 1 Comm: systemd-shutdow Tainted: G        W          6.1.0-rt5-00325-g8a5f56bcfcca #8
>   Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
>   Call trace:
>    tty_driver_flush_buffer+0x4/0x30
>    serdev_device_write_flush+0x24/0x34
>    qca_serdev_shutdown+0x80/0x130 [hci_uart]
>    device_shutdown+0x15c/0x260
>    kernel_restart+0x48/0xac
> 
> KASAN report:
> 
>   BUG: KASAN: use-after-free in tty_driver_flush_buffer+0x1c/0x50
>   Read of size 8 at addr ffff16270c2e0018 by task systemd-shutdow/1
> 
>   CPU: 7 PID: 1 Comm: systemd-shutdow Not tainted 6.1.0-next-20221220-00014-gb85aaf97fb01-dirty #28
>   Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
>   Call trace:
>    dump_backtrace.part.0+0xdc/0xf0
>    show_stack+0x18/0x30
>    dump_stack_lvl+0x68/0x84
>    print_report+0x188/0x488
>    kasan_report+0xa4/0xf0
>    __asan_load8+0x80/0xac
>    tty_driver_flush_buffer+0x1c/0x50
>    ttyport_write_flush+0x34/0x44
>    serdev_device_write_flush+0x48/0x60
>    qca_serdev_shutdown+0x124/0x274
>    device_shutdown+0x1e8/0x350
>    kernel_restart+0x48/0xb0
>    __do_sys_reboot+0x244/0x2d0
>    __arm64_sys_reboot+0x54/0x70
>    invoke_syscall+0x60/0x190
>    el0_svc_common.constprop.0+0x7c/0x160
>    do_el0_svc+0x44/0xf0
>    el0_svc+0x2c/0x6c
>    el0t_64_sync_handler+0xbc/0x140
>    el0t_64_sync+0x190/0x194
> 
> Fixes: 7e7bbddd029b ("Bluetooth: hci_qca: Fix qca6390 enable failure after warm reboot")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> ---

Any comments on this? Patchwork tools complain on longer line, but
without it checkpatch would complain as well, so I assume you do not
expect to fix it?

Best regards,
Krzysztof