[PATCH] drm: Fix potential null-ptr-deref due to drmm_mode_config_init()

[Thomas Zimmermann]

Hi,

merged into drm-misc-next. Thanks a lot.

Best regards
Thomas

Am 18.11.22 um 03:16 schrieb Shang XiaoJing:
> drmm_mode_config_init() will call drm_mode_create_standard_properties()
> and won't check the ret value. When drm_mode_create_standard_properties()
> failed due to alloc, property will be a NULL pointer and may causes the
> null-ptr-deref. Fix the null-ptr-deref by adding the ret value check.
> 
> Found null-ptr-deref while testing insert module bochs:
> general protection fault, probably for non-canonical address
>      0xdffffc000000000c: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
> CPU: 3 PID: 249 Comm: modprobe Not tainted 6.1.0-rc1+ #364
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014
> RIP: 0010:drm_object_attach_property+0x73/0x3c0 [drm]
> Call Trace:
>   <TASK>
>   __drm_connector_init+0xb6c/0x1100 [drm]
>   bochs_pci_probe.cold.11+0x4cb/0x7fe [bochs]
>   pci_device_probe+0x17d/0x340
>   really_probe+0x1db/0x5d0
>   __driver_probe_device+0x1e7/0x250
>   driver_probe_device+0x4a/0x120
>   __driver_attach+0xcd/0x2c0
>   bus_for_each_dev+0x11a/0x1b0
>   bus_add_driver+0x3d7/0x500
>   driver_register+0x18e/0x320
>   do_one_initcall+0xc4/0x3e0
>   do_init_module+0x1b4/0x630
>   load_module+0x5dca/0x7230
>   __do_sys_finit_module+0x100/0x170
>   do_syscall_64+0x3f/0x90
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7ff65af9f839
> 
> Fixes: 6b4959f43a04 ("drm/atomic: atomic plane properties")
> Signed-off-by: Shang XiaoJing <shangxiaojing at huawei.com>
> ---
>   drivers/gpu/drm/drm_mode_config.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 939d621c9ad4..141a5b4042b2 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -402,6 +402,8 @@ static void drm_mode_config_init_release(struct drm_device *dev, void *ptr)
>    */
>   int drmm_mode_config_init(struct drm_device *dev)
>   {
> +	int ret;
> +
>   	mutex_init(&dev->mode_config.mutex);
>   	drm_modeset_lock_init(&dev->mode_config.connection_mutex);
>   	mutex_init(&dev->mode_config.idr_mutex);
> @@ -423,7 +425,11 @@ int drmm_mode_config_init(struct drm_device *dev)
>   	init_llist_head(&dev->mode_config.connector_free_list);
>   	INIT_WORK(&dev->mode_config.connector_free_work, drm_connector_free_work_fn);
>   
> -	drm_mode_create_standard_properties(dev);
> +	ret = drm_mode_create_standard_properties(dev);
> +	if (ret) {
> +		drm_mode_config_cleanup(dev);
> +		return ret;
> +	}
>   
>   	/* Just to be sure */
>   	dev->mode_config.num_fb = 0;

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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