On Sat, Oct 9, 2021 at 9:32 AM Yang Yingliang <yangyingliang@xxxxxxxxxx> wrote:
>
> I got the double free report:
>
> [ 68.308365][ T359] BUG: KASAN: double-free or invalid-free in kfree+0xce/0x390
> [ 68.309532][ T359]
> [ 68.309886][ T359] CPU: 0 PID: 359 Comm: xrun Tainted: G W 5.15.0-rc3-00109-g4dfd49fafc4d-dirty #474 523b7f3c65c42247635e2ac04a95f61f9f36678d
> [ 68.312059][ T359] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
> [ 68.313566][ T359] Call Trace:
> [ 68.314063][ T359] dump_stack_lvl+0xe2/0x152
> [ 68.314793][ T359] print_address_description.constprop.7+0x21/0x150
> [ 68.315842][ T359] ? kfree+0xce/0x390
> [ 68.316444][ T359] kasan_report_invalid_free+0x6f/0xa0
> [ 68.317289][ T359] ? kfree+0xce/0x390
> [ 68.317902][ T359] __kasan_slab_free+0x125/0x140
> [ 68.318660][ T359] slab_free_freelist_hook+0x10d/0x240
> [ 68.319497][ T359] ? iio_device_unregister_sysfs+0x108/0x13b [industrialio]
> [ 68.321179][ T359] kfree+0xce/0x390
> [ 68.321781][ T359] iio_device_unregister_sysfs+0x108/0x13b [industrialio]
> [ 68.323438][ T359] iio_dev_release+0x9e/0x10e [industrialio]
> [ 68.324902][ T359] ? iio_device_unregister_sysfs+0x13b/0x13b [industrialio]
> [ 68.326550][ T359] device_release+0xa5/0x240
> [ 68.327258][ T359] kobject_put+0x1e5/0x540
> [ 68.327954][ T359] put_device+0x20/0x30
> [ 68.328612][ T359] devm_iio_device_release+0x21/0x30 [industrialio]
> [ 68.330172][ T359] release_nodes+0xc3/0x3b0
> [ 68.330874][ T359] ? __sanitizer_cov_trace_pc+0x1d/0x50
> [ 68.331765][ T359] ? _raw_spin_unlock_irqrestore+0x4b/0x5d
> [ 68.332668][ T359] ? trace_hardirqs_on+0x63/0x2d0
> [ 68.333509][ T359] devres_release_group+0x1da/0x2c0
> [ 68.334325][ T359] ? release_nodes+0x3b0/0x3b0
> [ 68.335069][ T359] ? __devm_iio_device_register+0x36/0x80 [industrialio]
> [ 68.336721][ T359] ? max517_probe+0x3df/0x6b0 [max517]
> [ 68.338122][ T359] i2c_device_probe+0x628/0xbb0
> [ 68.338886][ T359] ? i2c_device_match+0x110/0x110
> [ 68.339674][ T359] really_probe+0x285/0xc30
>
> If __iio_device_register() fails, iio_dev_opaque->groups will be freed
> in error path in iio_device_unregister_sysfs(), then iio_dev_release()
> will call iio_device_unregister_sysfs() again, it causes double free.
> Set iio_dev_opaque->groups to NULL when it's freed to fix this double free.
>
Thanks for catching this.
Reviewed-by: Alexandru Ardelean <ardeleanalex@xxxxxxxxx>
> Fixes: 32f171724e5c ("iio: core: rework iio device group creation")
> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> ---
> drivers/iio/industrialio-core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 2dbb37e09b8c..2dc837db50f7 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -1600,6 +1600,7 @@ static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
> kfree(iio_dev_opaque->chan_attr_group.attrs);
> iio_dev_opaque->chan_attr_group.attrs = NULL;
> kfree(iio_dev_opaque->groups);
> + iio_dev_opaque->groups = NULL;
> }
>
> static void iio_dev_release(struct device *device)
> --
> 2.25.1
>
