* [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition @ 2023-03-10 9:12 Zheng Wang 2023-03-18 17:39 ` Jonathan Cameron 2023-03-20 9:35 ` Nicolas Ferre 0 siblings, 2 replies; 9+ messages in thread From: Zheng Wang @ 2023-03-10 9:12 UTC (permalink / raw) To: eugen.hristev Cc: jic23, lars, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel, Zheng Wang In at91_adc_probe, &st->touch_st.workq is bound with at91_adc_workq_handler. Then it will be started by irq handler at91_adc_touch_data_handler If we remove the driver which will call at91_adc_remove to make cleanup, there may be a unfinished work. The possible sequence is as follows: Fix it by finishing the work before cleanup in the at91_adc_remove CPU0 CPU1 |at91_adc_workq_handler at91_adc_remove | iio_device_unregister| iio_dev_release | kfree(iio_dev_opaque);| | |iio_push_to_buffers |&iio_dev_opaque->buffer_list |//use Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") Signed-off-by: Zheng Wang <zyytlz.wz@163.com> --- drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c index 50d02e5fc6fc..1b95d18d9e0b 100644 --- a/drivers/iio/adc/at91-sama5d2_adc.c +++ b/drivers/iio/adc/at91-sama5d2_adc.c @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) struct iio_dev *indio_dev = platform_get_drvdata(pdev); struct at91_adc_state *st = iio_priv(indio_dev); + disable_irq_nosync(st->irq); + cancel_work_sync(&st->touch_st.workq); iio_device_unregister(indio_dev); at91_adc_dma_disable(st); -- 2.25.1 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-10 9:12 [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition Zheng Wang @ 2023-03-18 17:39 ` Jonathan Cameron 2023-03-18 17:36 ` Lars-Peter Clausen 2023-03-20 3:40 ` 王征 2023-03-20 9:35 ` Nicolas Ferre 1 sibling, 2 replies; 9+ messages in thread From: Jonathan Cameron @ 2023-03-18 17:39 UTC (permalink / raw) To: Zheng Wang Cc: eugen.hristev, lars, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel On Fri, 10 Mar 2023 17:12:39 +0800 Zheng Wang <zyytlz.wz@163.com> wrote: > In at91_adc_probe, &st->touch_st.workq is bound with > at91_adc_workq_handler. Then it will be started by irq > handler at91_adc_touch_data_handler > > If we remove the driver which will call at91_adc_remove > to make cleanup, there may be a unfinished work. > > The possible sequence is as follows: > > Fix it by finishing the work before cleanup in the at91_adc_remove > > CPU0 CPU1 > > |at91_adc_workq_handler > at91_adc_remove | > iio_device_unregister| > iio_dev_release | > kfree(iio_dev_opaque);| > | > |iio_push_to_buffers > |&iio_dev_opaque->buffer_list > |//use > Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") > Signed-off-by: Zheng Wang <zyytlz.wz@163.com> > --- > drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c > index 50d02e5fc6fc..1b95d18d9e0b 100644 > --- a/drivers/iio/adc/at91-sama5d2_adc.c > +++ b/drivers/iio/adc/at91-sama5d2_adc.c > @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) > struct iio_dev *indio_dev = platform_get_drvdata(pdev); > struct at91_adc_state *st = iio_priv(indio_dev); > > + disable_irq_nosync(st->irq); > + cancel_work_sync(&st->touch_st.workq); I'd like some input form someone more familiar with this driver than I am. In particular, whilst it fixes the bug seen I'm not sure what the most logical ordering for the disable is or the best way to do it. I'd prefer to see the irq cut off at source by disabling it at the device feature that is generating the irq followed by cancelling or waiting for completion of any in flight work. > iio_device_unregister(indio_dev); > > at91_adc_dma_disable(st); ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-18 17:39 ` Jonathan Cameron @ 2023-03-18 17:36 ` Lars-Peter Clausen 2023-03-19 15:22 ` Jonathan Cameron 2023-03-20 3:41 ` 王征 2023-03-20 3:40 ` 王征 1 sibling, 2 replies; 9+ messages in thread From: Lars-Peter Clausen @ 2023-03-18 17:36 UTC (permalink / raw) To: Jonathan Cameron, Zheng Wang Cc: eugen.hristev, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel On 3/18/23 10:39, Jonathan Cameron wrote: > On Fri, 10 Mar 2023 17:12:39 +0800 > Zheng Wang <zyytlz.wz@163.com> wrote: > >> In at91_adc_probe, &st->touch_st.workq is bound with >> at91_adc_workq_handler. Then it will be started by irq >> handler at91_adc_touch_data_handler >> >> If we remove the driver which will call at91_adc_remove >> to make cleanup, there may be a unfinished work. >> >> The possible sequence is as follows: >> >> Fix it by finishing the work before cleanup in the at91_adc_remove >> >> CPU0 CPU1 >> >> |at91_adc_workq_handler >> at91_adc_remove | >> iio_device_unregister| >> iio_dev_release | >> kfree(iio_dev_opaque);| >> | >> |iio_push_to_buffers >> |&iio_dev_opaque->buffer_list >> |//use >> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") >> Signed-off-by: Zheng Wang <zyytlz.wz@163.com> >> --- >> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c >> index 50d02e5fc6fc..1b95d18d9e0b 100644 >> --- a/drivers/iio/adc/at91-sama5d2_adc.c >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c >> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) >> struct iio_dev *indio_dev = platform_get_drvdata(pdev); >> struct at91_adc_state *st = iio_priv(indio_dev); >> >> + disable_irq_nosync(st->irq); >> + cancel_work_sync(&st->touch_st.workq); > I'd like some input form someone more familiar with this driver than I am. > > In particular, whilst it fixes the bug seen I'm not sure what the most > logical ordering for the disable is or the best way to do it. > > I'd prefer to see the irq cut off at source by disabling it at the device > feature that is generating the irq followed by cancelling or waiting for > completion of any in flight work. The usually way you'd do this by calling free_irq() before the cancel_work_sync(). ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-18 17:36 ` Lars-Peter Clausen @ 2023-03-19 15:22 ` Jonathan Cameron 2023-03-20 3:54 ` 王征 2023-03-20 3:41 ` 王征 1 sibling, 1 reply; 9+ messages in thread From: Jonathan Cameron @ 2023-03-19 15:22 UTC (permalink / raw) To: Lars-Peter Clausen Cc: Zheng Wang, eugen.hristev, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel On Sat, 18 Mar 2023 10:36:04 -0700 Lars-Peter Clausen <lars@metafoo.de> wrote: > On 3/18/23 10:39, Jonathan Cameron wrote: > > On Fri, 10 Mar 2023 17:12:39 +0800 > > Zheng Wang <zyytlz.wz@163.com> wrote: > > > >> In at91_adc_probe, &st->touch_st.workq is bound with > >> at91_adc_workq_handler. Then it will be started by irq > >> handler at91_adc_touch_data_handler > >> > >> If we remove the driver which will call at91_adc_remove > >> to make cleanup, there may be a unfinished work. > >> > >> The possible sequence is as follows: > >> > >> Fix it by finishing the work before cleanup in the at91_adc_remove > >> > >> CPU0 CPU1 > >> > >> |at91_adc_workq_handler > >> at91_adc_remove | > >> iio_device_unregister| > >> iio_dev_release | > >> kfree(iio_dev_opaque);| > >> | > >> |iio_push_to_buffers > >> |&iio_dev_opaque->buffer_list > >> |//use > >> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") > >> Signed-off-by: Zheng Wang <zyytlz.wz@163.com> > >> --- > >> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c > >> index 50d02e5fc6fc..1b95d18d9e0b 100644 > >> --- a/drivers/iio/adc/at91-sama5d2_adc.c > >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c > >> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) > >> struct iio_dev *indio_dev = platform_get_drvdata(pdev); > >> struct at91_adc_state *st = iio_priv(indio_dev); > >> > >> + disable_irq_nosync(st->irq); > >> + cancel_work_sync(&st->touch_st.workq); > > I'd like some input form someone more familiar with this driver than I am. > > > > In particular, whilst it fixes the bug seen I'm not sure what the most > > logical ordering for the disable is or the best way to do it. > > > > I'd prefer to see the irq cut off at source by disabling it at the device > > feature that is generating the irq followed by cancelling or waiting for > > completion of any in flight work. > The usually way you'd do this by calling free_irq() before the > cancel_work_sync(). I'd go a little further than that and disable the interrupt source at the device (if possible) then call free_irq() then cancel_work_sync() Otherwise the device is merrily monitoring something and generating interrupts that we don't care about. Might well be wasting power doing that, though I haven't checked the flow in this particular case. Jonathan ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re:Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-19 15:22 ` Jonathan Cameron @ 2023-03-20 3:54 ` 王征 0 siblings, 0 replies; 9+ messages in thread From: 王征 @ 2023-03-20 3:54 UTC (permalink / raw) To: Jonathan Cameron Cc: eugen.hristev, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel, Lars-Peter Clausen, hackerzheng666, alex000young, 1395428693sheep At 2023-03-19 22:22:22, "Jonathan Cameron" <jic23@kernel.org> wrote: >On Sat, 18 Mar 2023 10:36:04 -0700 >Lars-Peter Clausen <lars@metafoo.de> wrote: > >> On 3/18/23 10:39, Jonathan Cameron wrote: >> > On Fri, 10 Mar 2023 17:12:39 +0800 >> > Zheng Wang <zyytlz.wz@163.com> wrote: >> > >> >> In at91_adc_probe, &st->touch_st.workq is bound with >> >> at91_adc_workq_handler. Then it will be started by irq >> >> handler at91_adc_touch_data_handler >> >> >> >> If we remove the driver which will call at91_adc_remove >> >> to make cleanup, there may be a unfinished work. >> >> >> >> The possible sequence is as follows: >> >> >> >> Fix it by finishing the work before cleanup in the at91_adc_remove >> >> >> >> CPU0 CPU1 >> >> >> >> |at91_adc_workq_handler >> >> at91_adc_remove | >> >> iio_device_unregister| >> >> iio_dev_release | >> >> kfree(iio_dev_opaque);| >> >> | >> >> |iio_push_to_buffers >> >> |&iio_dev_opaque->buffer_list >> >> |//use >> >> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") >> >> Signed-off-by: Zheng Wang <zyytlz.wz@163.com> >> >> --- >> >> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ >> >> 1 file changed, 2 insertions(+) >> >> >> >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c >> >> index 50d02e5fc6fc..1b95d18d9e0b 100644 >> >> --- a/drivers/iio/adc/at91-sama5d2_adc.c >> >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c >> >> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) >> >> struct iio_dev *indio_dev = platform_get_drvdata(pdev); >> >> struct at91_adc_state *st = iio_priv(indio_dev); >> >> >> >> + disable_irq_nosync(st->irq); >> >> + cancel_work_sync(&st->touch_st.workq); >> > I'd like some input form someone more familiar with this driver than I am. >> > >> > In particular, whilst it fixes the bug seen I'm not sure what the most >> > logical ordering for the disable is or the best way to do it. >> > >> > I'd prefer to see the irq cut off at source by disabling it at the device >> > feature that is generating the irq followed by cancelling or waiting for >> > completion of any in flight work. >> The usually way you'd do this by calling free_irq() before the >> cancel_work_sync(). > >I'd go a little further than that and disable the interrupt source at the >device (if possible) then call free_irq() then cancel_work_sync() > >Otherwise the device is merrily monitoring something and generating interrupts >that we don't care about. Might well be wasting power doing that, though I haven't >checked the flow in this particular case. > Dear Lars-Peter Clausen, Thank you for your response to my question. I appreciate your suggestion to disable the interrupt source at the device before calling free_irq() and cancel_work_sync(). However, I am not sure which specific function to use in order to achieve this. Can you please provide more information on which function to use and how to use it? Thank you very much for your help. Best regards, Zheng Wang >Jonathan ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re:Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-18 17:36 ` Lars-Peter Clausen 2023-03-19 15:22 ` Jonathan Cameron @ 2023-03-20 3:41 ` 王征 1 sibling, 0 replies; 9+ messages in thread From: 王征 @ 2023-03-20 3:41 UTC (permalink / raw) To: Lars-Peter Clausen Cc: Jonathan Cameron, eugen.hristev, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel At 2023-03-19 00:36:04, "Lars-Peter Clausen" <lars@metafoo.de> wrote: >On 3/18/23 10:39, Jonathan Cameron wrote: >> On Fri, 10 Mar 2023 17:12:39 +0800 >> Zheng Wang <zyytlz.wz@163.com> wrote: >> >>> In at91_adc_probe, &st->touch_st.workq is bound with >>> at91_adc_workq_handler. Then it will be started by irq >>> handler at91_adc_touch_data_handler >>> >>> If we remove the driver which will call at91_adc_remove >>> to make cleanup, there may be a unfinished work. >>> >>> The possible sequence is as follows: >>> >>> Fix it by finishing the work before cleanup in the at91_adc_remove >>> >>> CPU0 CPU1 >>> >>> |at91_adc_workq_handler >>> at91_adc_remove | >>> iio_device_unregister| >>> iio_dev_release | >>> kfree(iio_dev_opaque);| >>> | >>> |iio_push_to_buffers >>> |&iio_dev_opaque->buffer_list >>> |//use >>> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") >>> Signed-off-by: Zheng Wang <zyytlz.wz@163.com> >>> --- >>> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c >>> index 50d02e5fc6fc..1b95d18d9e0b 100644 >>> --- a/drivers/iio/adc/at91-sama5d2_adc.c >>> +++ b/drivers/iio/adc/at91-sama5d2_adc.c >>> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) >>> struct iio_dev *indio_dev = platform_get_drvdata(pdev); >>> struct at91_adc_state *st = iio_priv(indio_dev); >>> >>> + disable_irq_nosync(st->irq); >>> + cancel_work_sync(&st->touch_st.workq); >> I'd like some input form someone more familiar with this driver than I am. >> >> In particular, whilst it fixes the bug seen I'm not sure what the most >> logical ordering for the disable is or the best way to do it. >> >> I'd prefer to see the irq cut off at source by disabling it at the device >> feature that is generating the irq followed by cancelling or waiting for >> completion of any in flight work. >The usually way you'd do this by calling free_irq() before the >cancel_work_sync(). Hi, Thank you for your response and feedback on my patch. I appreciate your input and would like to address your concerns. Regarding the best way to disable the IRQ, I agree that calling free_irq() before cancel_work_sync() would be a better approach. This ensures that the IRQ is completely disabled at the source, and any in-flight work is finished before removing the driver. I will make this change in the patch. Best regards, Zheng Wang > ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re:Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-18 17:39 ` Jonathan Cameron 2023-03-18 17:36 ` Lars-Peter Clausen @ 2023-03-20 3:40 ` 王征 1 sibling, 0 replies; 9+ messages in thread From: 王征 @ 2023-03-20 3:40 UTC (permalink / raw) To: Jonathan Cameron Cc: eugen.hristev, lars, nicolas.ferre, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel At 2023-03-19 00:39:13, "Jonathan Cameron" <jic23@kernel.org> wrote: >On Fri, 10 Mar 2023 17:12:39 +0800 >Zheng Wang <zyytlz.wz@163.com> wrote: > >> In at91_adc_probe, &st->touch_st.workq is bound with >> at91_adc_workq_handler. Then it will be started by irq >> handler at91_adc_touch_data_handler >> >> If we remove the driver which will call at91_adc_remove >> to make cleanup, there may be a unfinished work. >> >> The possible sequence is as follows: >> >> Fix it by finishing the work before cleanup in the at91_adc_remove >> >> CPU0 CPU1 >> >> |at91_adc_workq_handler >> at91_adc_remove | >> iio_device_unregister| >> iio_dev_release | >> kfree(iio_dev_opaque);| >> | >> |iio_push_to_buffers >> |&iio_dev_opaque->buffer_list >> |//use >> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") >> Signed-off-by: Zheng Wang <zyytlz.wz@163.com> >> --- >> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c >> index 50d02e5fc6fc..1b95d18d9e0b 100644 >> --- a/drivers/iio/adc/at91-sama5d2_adc.c >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c >> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) >> struct iio_dev *indio_dev = platform_get_drvdata(pdev); >> struct at91_adc_state *st = iio_priv(indio_dev); >> >> + disable_irq_nosync(st->irq); >> + cancel_work_sync(&st->touch_st.workq); > >I'd like some input form someone more familiar with this driver than I am. > >In particular, whilst it fixes the bug seen I'm not sure what the most >logical ordering for the disable is or the best way to do it. > >I'd prefer to see the irq cut off at source by disabling it at the device >feature that is generating the irq followed by cancelling or waiting for >completion of any in flight work. Hi, Sorry for my late reply. I think we need to replace disable_irq_nosync with free_irq. Thanks, Zheng > >> iio_device_unregister(indio_dev); >> >> at91_adc_dma_disable(st); ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-10 9:12 [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition Zheng Wang 2023-03-18 17:39 ` Jonathan Cameron @ 2023-03-20 9:35 ` Nicolas Ferre 2023-03-20 12:07 ` 王征 1 sibling, 1 reply; 9+ messages in thread From: Nicolas Ferre @ 2023-03-20 9:35 UTC (permalink / raw) To: Zheng Wang, eugen.hristev Cc: jic23, lars, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel On 10/03/2023 at 10:12, Zheng Wang wrote: > In at91_adc_probe, &st->touch_st.workq is bound with > at91_adc_workq_handler. Then it will be started by irq > handler at91_adc_touch_data_handler > > If we remove the driver which will call at91_adc_remove > to make cleanup, there may be a unfinished work. > > The possible sequence is as follows: > > Fix it by finishing the work before cleanup in the at91_adc_remove > > CPU0 CPU1 > > |at91_adc_workq_handler > at91_adc_remove | > iio_device_unregister| > iio_dev_release | > kfree(iio_dev_opaque);| > | > |iio_push_to_buffers > |&iio_dev_opaque->buffer_list > |//use There is no such thing as a SMP platform using this driver (yet?), so we agree that this fix is purely theoretical, cannot be reproduced nor its fix validated. That being said, I'm happy that enhancements are provided to this driver, no doubt about that. > Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") > Signed-off-by: Zheng Wang <zyytlz.wz@163.com> > --- > drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c > index 50d02e5fc6fc..1b95d18d9e0b 100644 > --- a/drivers/iio/adc/at91-sama5d2_adc.c > +++ b/drivers/iio/adc/at91-sama5d2_adc.c > @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) > struct iio_dev *indio_dev = platform_get_drvdata(pdev); > struct at91_adc_state *st = iio_priv(indio_dev); > > + disable_irq_nosync(st->irq); > + cancel_work_sync(&st->touch_st.workq); About stopping the source of interrupt, I would recommend using a sequence already exposed in at91_adc_hw_init (and possibly make it common), like: if (st->soc_info.platform->layout->EOC_IDR) at91_adc_writel(st, EOC_IDR, 0xffffffff); at91_adc_writel(st, IDR, 0xffffffff); Regards, Nicolas > iio_device_unregister(indio_dev); > > at91_adc_dma_disable(st); > -- > 2.25.1 > -- Nicolas Ferre ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re:Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition 2023-03-20 9:35 ` Nicolas Ferre @ 2023-03-20 12:07 ` 王征 0 siblings, 0 replies; 9+ messages in thread From: 王征 @ 2023-03-20 12:07 UTC (permalink / raw) To: Nicolas Ferre Cc: eugen.hristev, jic23, lars, alexandre.belloni, claudiu.beznea, linux-iio, linux-arm-kernel, linux-kernel, hackerzheng666, 1395428693sheep, alex000young At 2023-03-20 16:35:24, "Nicolas Ferre" <nicolas.ferre@microchip.com> wrote: >On 10/03/2023 at 10:12, Zheng Wang wrote: >> In at91_adc_probe, &st->touch_st.workq is bound with >> at91_adc_workq_handler. Then it will be started by irq >> handler at91_adc_touch_data_handler >> >> If we remove the driver which will call at91_adc_remove >> to make cleanup, there may be a unfinished work. >> >> The possible sequence is as follows: >> >> Fix it by finishing the work before cleanup in the at91_adc_remove >> >> CPU0 CPU1 >> >> |at91_adc_workq_handler >> at91_adc_remove | >> iio_device_unregister| >> iio_dev_release | >> kfree(iio_dev_opaque);| >> | >> |iio_push_to_buffers >> |&iio_dev_opaque->buffer_list >> |//use > >There is no such thing as a SMP platform using this driver (yet?), so we >agree that this fix is purely theoretical, cannot be reproduced nor its >fix validated. > >That being said, I'm happy that enhancements are provided to this >driver, no doubt about that. > Hi Nicolas, Thanks for your reply. I'm not familiar with the module and I think you're right. > >> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") >> Signed-off-by: Zheng Wang <zyytlz.wz@163.com> >> --- >> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c >> index 50d02e5fc6fc..1b95d18d9e0b 100644 >> --- a/drivers/iio/adc/at91-sama5d2_adc.c >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c >> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) >> struct iio_dev *indio_dev = platform_get_drvdata(pdev); >> struct at91_adc_state *st = iio_priv(indio_dev); >> >> + disable_irq_nosync(st->irq); >> + cancel_work_sync(&st->touch_st.workq); > >About stopping the source of interrupt, I would recommend using a >sequence already exposed in at91_adc_hw_init (and possibly make it >common), like: > > if (st->soc_info.platform->layout->EOC_IDR) > at91_adc_writel(st, EOC_IDR, 0xffffffff); > at91_adc_writel(st, IDR, 0xffffffff); > Thanks fou your advice. I'll apply it in the next version. Best regards, Zheng >Regards, > Nicolas > >> iio_device_unregister(indio_dev); >> >> at91_adc_dma_disable(st); >> -- >> 2.25.1 >> > >-- >Nicolas Ferre ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-03-20 12:08 UTC | newest] Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-03-10 9:12 [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition Zheng Wang 2023-03-18 17:39 ` Jonathan Cameron 2023-03-18 17:36 ` Lars-Peter Clausen 2023-03-19 15:22 ` Jonathan Cameron 2023-03-20 3:54 ` 王征 2023-03-20 3:41 ` 王征 2023-03-20 3:40 ` 王征 2023-03-20 9:35 ` Nicolas Ferre 2023-03-20 12:07 ` 王征
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