Re: [PATCH 1/2] soundwire: intel: fix possible crash when no device is detected

["Rafael J. Wysocki" <rafael@kernel.org>]

On Mon, Feb 8, 2021 at 1:01 PM Marcin Ślusarz <marcin.slusarz@gmail.com> wrote:
>
> From: Marcin Ślusarz <marcin.slusarz@intel.com>
>
> acpi_walk_namespace can return success without executing our
> callback which initializes info->handle.
> If the random value in this structure is a valid address (which
> is on the stack, so it's quite possible), then nothing bad will
> happen, because:
> sdw_intel_scan_controller
>  -> acpi_bus_get_device
>  -> acpi_get_device_data
>  -> acpi_get_data_full
>  -> acpi_ns_validate_handle
> will reject this handle.
>
> However, if the value from the stack doesn't point to a valid
> address, we get this:
>
> BUG: kernel NULL pointer dereference, address: 0000000000000050
> PGD 0 P4D 0
> Oops: 0000 [#1] SMP NOPTI
> CPU: 6 PID: 472 Comm: systemd-udevd Tainted: G        W         5.10.0-1-amd64 #1 Debian 5.10.4-1
> Hardware name: HP HP Pavilion Laptop 15-cs3xxx/86E2, BIOS F.05 01/01/2020
> RIP: 0010:acpi_ns_validate_handle+0x1a/0x23
> Code: 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 44 00 00 48 8d 57 ff 48 89 f8 48 83 fa fd 76 08 48 8b 05 0c b8 67 01 c3 <80> 7f 08 0f 74 02 31 c0 c3 0f 1f 44 00 00 48 8b 3d f6 b7 67 01 e8
> RSP: 0000:ffffc388807c7b20 EFLAGS: 00010213
> RAX: 0000000000000048 RBX: ffffc388807c7b70 RCX: 0000000000000000
> RDX: 0000000000000047 RSI: 0000000000000246 RDI: 0000000000000048
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffffc0f5f4d1 R11: ffffffff8f0cb268 R12: 0000000000001001
> R13: ffffffff8e33b160 R14: 0000000000000048 R15: 0000000000000000
> FS:  00007f24548288c0(0000) GS:ffff9f781fb80000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000050 CR3: 0000000106158004 CR4: 0000000000770ee0
> PKRU: 55555554
> Call Trace:
>  acpi_get_data_full+0x4d/0x92
>  acpi_bus_get_device+0x1f/0x40
>  sdw_intel_acpi_scan+0x59/0x230 [soundwire_intel]
>  ? strstr+0x22/0x60
>  ? dmi_matches+0x76/0xe0
>  snd_intel_dsp_driver_probe.cold+0xaf/0x163 [snd_intel_dspcfg]
>  azx_probe+0x7a/0x970 [snd_hda_intel]
>  local_pci_probe+0x42/0x80
>  ? _cond_resched+0x16/0x40
>  pci_device_probe+0xfd/0x1b0
>  really_probe+0x205/0x460
>  driver_probe_device+0xe1/0x150
>  device_driver_attach+0xa1/0xb0
>  __driver_attach+0x8a/0x150
>  ? device_driver_attach+0xb0/0xb0
>  ? device_driver_attach+0xb0/0xb0
>  bus_for_each_dev+0x78/0xc0
>  bus_add_driver+0x12b/0x1e0
>  driver_register+0x8b/0xe0
>  ? 0xffffffffc0f65000
>  do_one_initcall+0x44/0x1d0
>  ? do_init_module+0x23/0x250
>  ? kmem_cache_alloc_trace+0xf5/0x200
>  do_init_module+0x5c/0x250
>  __do_sys_finit_module+0xb1/0x110
>  do_syscall_64+0x33/0x80
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> CC: stable@vger.kernel.org
> Signed-off-by: Marcin Ślusarz <marcin.slusarz@intel.com>
> Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/soundwire/intel_init.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
> index cabdadb09a1b..bc8520eb385e 100644
> --- a/drivers/soundwire/intel_init.c
> +++ b/drivers/soundwire/intel_init.c
> @@ -405,11 +405,12 @@ int sdw_intel_acpi_scan(acpi_handle *parent_handle,
>  {
>         acpi_status status;
>
> +       info->handle = NULL;
>         status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
>                                      parent_handle, 1,
>                                      sdw_intel_acpi_cb,
>                                      NULL, info, NULL);
> -       if (ACPI_FAILURE(status))
> +       if (ACPI_FAILURE(status) || info->handle == NULL)
>                 return -ENODEV;
>
>         return sdw_intel_scan_controller(info);
> --
> 2.25.1
>