Re: [PATCH 2/2] hwtracing: stm: fix double-free in stm_source_register_device()

[Kefeng Wang]

sorry, send wrong version, please ignore.

On 2019/5/20 17:13, Kefeng Wang wrote:
> If device_add() in stm_source_register_device() fails,
> stm_source_device_release() is called to free src, free
> src again on err path will trigger double free issue.
>
> BUG: KASAN: double-free or invalid-free in stm_source_register_device+0xd0/0x1a0 [stm_core]
>
> CPU: 1 PID: 8556 Comm: syz-executor.0 Tainted: G         C        5.1.0+ #28
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0xa9/0x10e lib/dump_stack.c:113
>  print_address_description+0x65/0x270 mm/kasan/report.c:188
>  kasan_report_invalid_free+0x60/0xa0 mm/kasan/report.c:279
>  __kasan_slab_free+0x159/0x180 mm/kasan/common.c:430
>  slab_free_hook mm/slub.c:1420 [inline]
>  slab_free_freelist_hook mm/slub.c:1447 [inline]
>  slab_free mm/slub.c:2994 [inline]
>  kfree+0xe1/0x270 mm/slub.c:3949
>  stm_source_register_device+0xd0/0x1a0 [stm_core]
>  stm_heartbeat_init+0xb6/0x1b0 [stm_heartbeat]
>  do_one_initcall+0xb9/0x3b5 init/main.c:914
>  do_init_module+0xe0/0x330 kernel/module.c:3468
>  load_module+0x38eb/0x4270 kernel/module.c:3819
>  __do_sys_finit_module+0x162/0x190 kernel/module.c:3909
>  do_syscall_64+0x72/0x2a0 arch/x86/entry/common.c:298
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
>  ...
>
> Allocated by task 8556:
>  save_stack+0x19/0x80 mm/kasan/common.c:71
>  set_track mm/kasan/common.c:79 [inline]
>  __kasan_kmalloc.constprop.2+0xa0/0xd0 mm/kasan/common.c:489
>  stm_source_register_device+0x46/0x1a0 [stm_core]
>  stm_heartbeat_init+0xb6/0x1b0 [stm_heartbeat]
>  do_one_initcall+0xb9/0x3b5 init/main.c:914
>  do_init_module+0xe0/0x330 kernel/module.c:3468
>  load_module+0x38eb/0x4270 kernel/module.c:3819
>  __do_sys_finit_module+0x162/0x190 kernel/module.c:3909
>  do_syscall_64+0x72/0x2a0 arch/x86/entry/common.c:298
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 8556:
>  save_stack+0x19/0x80 mm/kasan/common.c:71
>  set_track mm/kasan/common.c:79 [inline]
>  __kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
>  slab_free_hook mm/slub.c:1420 [inline]
>  slab_free_freelist_hook mm/slub.c:1447 [inline]
>  slab_free mm/slub.c:2994 [inline]
>  kfree+0xe1/0x270 mm/slub.c:3949
>  device_release+0x46/0x100 drivers/base/core.c:1064
>  kobject_cleanup lib/kobject.c:691 [inline]
>  kobject_release lib/kobject.c:720 [inline]
>  kref_put include/linux/kref.h:67 [inline]
>  kobject_put+0x1a8/0x220 lib/kobject.c:737
>  put_device+0x1b/0x30 drivers/base/core.c:2210
>  stm_source_register_device+0xc8/0x1a0 [stm_core]
>  stm_heartbeat_init+0xb6/0x1b0 [stm_heartbeat]
>  do_one_initcall+0xb9/0x3b5 init/main.c:914
>  do_init_module+0xe0/0x330 kernel/module.c:3468
>  load_module+0x38eb/0x4270 kernel/module.c:3819
>  __do_sys_finit_module+0x162/0x190 kernel/module.c:3909
>  do_syscall_64+0x72/0x2a0 arch/x86/entry/common.c:298
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Don't call kfree(src) if device_add() fails to fix it.
>
> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> ---
>  drivers/hwtracing/stm/core.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
> index 7b2ab7b2cc4d..5ce30f8f8c4f 100644
> --- a/drivers/hwtracing/stm/core.c
> +++ b/drivers/hwtracing/stm/core.c
> @@ -1258,15 +1258,20 @@ int stm_source_register_device(struct device *parent,
>  	src->dev.release = stm_source_device_release;
>  
>  	err = kobject_set_name(&src->dev.kobj, "%s", data->name);
> -	if (err)
> +	if (err) {
> +		put_device(&src->dev);
> +		kfree(src);
>  		goto err;
> +	}
>  
>  	pm_runtime_no_callbacks(&src->dev);
>  	pm_runtime_forbid(&src->dev);
>  
>  	err = device_add(&src->dev);
> -	if (err)
> -		goto err;
> +	if (err) {
> +		put_device(&src->dev);
> +		return err;
> +	}
>  
>  	stm_output_init(&src->output);
>  	spin_lock_init(&src->link_lock);
> @@ -1275,12 +1280,6 @@ int stm_source_register_device(struct device *parent,
>  	data->src = src;
>  
>  	return 0;
> -
> -err:
> -	put_device(&src->dev);
> -	kfree(src);
> -
> -	return err;
>  }
>  EXPORT_SYMBOL_GPL(stm_source_register_device);
>