Re: [PATCH v1] hwmon: Fix double-free in __hwmon_device_register()

[linux]

Quoting Dmitry Osipenko <digetx@xxxxxxxxx>:

> Fix double-free that happens when thermal zone setup fails, see KASAN log
> below.

Good catch. I'll apply this as soon as I manage to convince AT&T to restore
my internet service.

Thanks,
Guenter

> ==================================================================
> BUG: KASAN: double-free or invalid-free in  
> __hwmon_device_register+0x5dc/0xa7c
>
> CPU: 0 PID: 132 Comm: kworker/0:2 Tainted: G    B              
> 4.19.0-rc8-next-20181016-00042-gb52cd80401e9-dirty #41
> Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
> Workqueue: events deferred_probe_work_func
> Backtrace:
> [<c0110540>] (dump_backtrace) from [<c0110944>] (show_stack+0x20/0x24)
> [<c0110924>] (show_stack) from [<c105cb08>] (dump_stack+0x9c/0xb0)
> [<c105ca6c>] (dump_stack) from [<c02fdaec>]  
> (print_address_description+0x68/0x250)
> [<c02fda84>] (print_address_description) from [<c02fd4ac>]  
> (kasan_report_invalid_free+0x68/0x88)
> [<c02fd444>] (kasan_report_invalid_free) from [<c02fc85c>]  
> (__kasan_slab_free+0x1f4/0x200)
> [<c02fc668>] (__kasan_slab_free) from [<c02fd0c0>]  
> (kasan_slab_free+0x14/0x18)
> [<c02fd0ac>] (kasan_slab_free) from [<c02f9c6c>] (kfree+0x90/0x294)
> [<c02f9bdc>] (kfree) from [<c0b41bbc>] (__hwmon_device_register+0x5dc/0xa7c)
> [<c0b415e0>] (__hwmon_device_register) from [<c0b421e8>]  
> (hwmon_device_register_with_info+0xa0/0xa8)
> [<c0b42148>] (hwmon_device_register_with_info) from [<c0b42324>]  
> (devm_hwmon_device_register_with_info+0x74/0xb4)
> [<c0b422b0>] (devm_hwmon_device_register_with_info) from  
> [<c0b4481c>] (lm90_probe+0x414/0x578)
> [<c0b44408>] (lm90_probe) from [<c0aeeff4>] (i2c_device_probe+0x35c/0x384)
> [<c0aeec98>] (i2c_device_probe) from [<c08776cc>] (really_probe+0x290/0x3e4)
> [<c087743c>] (really_probe) from [<c0877a2c>]  
> (driver_probe_device+0x80/0x1c4)
> [<c08779ac>] (driver_probe_device) from [<c0877da8>]  
> (__device_attach_driver+0x104/0x11c)
> [<c0877ca4>] (__device_attach_driver) from [<c0874dd8>]  
> (bus_for_each_drv+0xa4/0xc8)
> [<c0874d34>] (bus_for_each_drv) from [<c08773b0>]  
> (__device_attach+0xf0/0x15c)
> [<c08772c0>] (__device_attach) from [<c0877e24>]  
> (device_initial_probe+0x1c/0x20)
> [<c0877e08>] (device_initial_probe) from [<c08762f4>]  
> (bus_probe_device+0xdc/0xec)
> [<c0876218>] (bus_probe_device) from [<c0876a08>]  
> (deferred_probe_work_func+0xa8/0xd4)
> [<c0876960>] (deferred_probe_work_func) from [<c01527c4>]  
> (process_one_work+0x3dc/0x96c)
> [<c01523e8>] (process_one_work) from [<c01541e0>] (worker_thread+0x4ec/0x8bc)
> [<c0153cf4>] (worker_thread) from [<c015b238>] (kthread+0x230/0x240)
> [<c015b008>] (kthread) from [<c01010bc>] (ret_from_fork+0x14/0x38)
> Exception stack(0xcf743fb0 to 0xcf743ff8)
> 3fa0:                                     00000000 00000000 00000000 00000000
> 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
>
> Allocated by task 132:
>  kasan_kmalloc.part.1+0x58/0xf4
>  kasan_kmalloc+0x90/0xa4
>  kmem_cache_alloc_trace+0x90/0x2a0
>  __hwmon_device_register+0xbc/0xa7c
>  hwmon_device_register_with_info+0xa0/0xa8
>  devm_hwmon_device_register_with_info+0x74/0xb4
>  lm90_probe+0x414/0x578
>  i2c_device_probe+0x35c/0x384
>  really_probe+0x290/0x3e4
>  driver_probe_device+0x80/0x1c4
>  __device_attach_driver+0x104/0x11c
>  bus_for_each_drv+0xa4/0xc8
>  __device_attach+0xf0/0x15c
>  device_initial_probe+0x1c/0x20
>  bus_probe_device+0xdc/0xec
>  deferred_probe_work_func+0xa8/0xd4
>  process_one_work+0x3dc/0x96c
>  worker_thread+0x4ec/0x8bc
>  kthread+0x230/0x240
>  ret_from_fork+0x14/0x38
>    (null)
>
> Freed by task 132:
>  __kasan_slab_free+0x12c/0x200
>  kasan_slab_free+0x14/0x18
>  kfree+0x90/0x294
>  hwmon_dev_release+0x1c/0x20
>  device_release+0x4c/0xe8
>  kobject_put+0xac/0x11c
>  device_unregister+0x2c/0x30
>  __hwmon_device_register+0xa58/0xa7c
>  hwmon_device_register_with_info+0xa0/0xa8
>  devm_hwmon_device_register_with_info+0x74/0xb4
>  lm90_probe+0x414/0x578
>  i2c_device_probe+0x35c/0x384
>  really_probe+0x290/0x3e4
>  driver_probe_device+0x80/0x1c4
>  __device_attach_driver+0x104/0x11c
>  bus_for_each_drv+0xa4/0xc8
>  __device_attach+0xf0/0x15c
>  device_initial_probe+0x1c/0x20
>  bus_probe_device+0xdc/0xec
>  deferred_probe_work_func+0xa8/0xd4
>  process_one_work+0x3dc/0x96c
>  worker_thread+0x4ec/0x8bc
>  kthread+0x230/0x240
>  ret_from_fork+0x14/0x38
>    (null)
>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.15+
> Fixes: 47c332deb8e8 ("hwmon: Deal with errors from the thermal subsystem")
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
>  drivers/hwmon/hwmon.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
> index 975c95169884..84f61cec6319 100644
> --- a/drivers/hwmon/hwmon.c
> +++ b/drivers/hwmon/hwmon.c
> @@ -649,8 +649,10 @@ __hwmon_device_register(struct device *dev,  
> const char *name, void *drvdata,
>  				if (info[i]->config[j] & HWMON_T_INPUT) {
>  					err = hwmon_thermal_add_sensor(dev,
>  								hwdev, j);
> -					if (err)
> -						goto free_device;
> +					if (err) {
> +						device_unregister(hdev);
> +						goto ida_remove;
> +					}
>  				}
>  			}
>  		}
> @@ -658,8 +660,6 @@ __hwmon_device_register(struct device *dev,  
> const char *name, void *drvdata,
>
>  	return hdev;
>
> -free_device:
> -	device_unregister(hdev);
>  free_hwmon:
>  	kfree(hwdev);
>  ida_remove:
> --
> 2.19.0