[PATCH v3] HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition

[PATCH v3] HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition

[Kaixin Wang]

In the ssi_protocol_probe() function, &ssi->work is bound with
ssip_xmit_work(), In ssip_pn_setup(), the ssip_pn_xmit() function
within the ssip_pn_ops structure is capable of starting the
work.

If we remove the module which will call ssi_protocol_remove()
to make a cleanup, it will free ssi through kfree(ssi),
while the work mentioned above will be used. The sequence
of operations that may lead to a UAF bug is as follows:

CPU0                                    CPU1

                        | ssip_xmit_work
ssi_protocol_remove     |
kfree(ssi);             |
                        | struct hsi_client *cl = ssi->cl;
                        | // use ssi

Fix it by ensuring that the work is canceled before proceeding
with the cleanup in ssi_protocol_remove().

Signed-off-by: Kaixin Wang <kxwang23@m.fudan.edu.cn>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

---
v3:
- refer to the functions in the form of func() in the description message.
- Link to v2: https://lore.kernel.org/r/20240914172142.328-1-kxwang23@m.fudan.edu.cn
v2:
- cancel the work in ssip_reset(), suggested by Sebastian
- add the Acked-by label from Andy
- Link to v1: https://lore.kernel.org/r/20240911151915.844957-1-kxwang23@m.fudan.edu.cn
---
 drivers/hsi/clients/ssi_protocol.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/hsi/clients/ssi_protocol.c b/drivers/hsi/clients/ssi_protocol.c
index afe470f3661c..6105ea9a6c6a 100644
--- a/drivers/hsi/clients/ssi_protocol.c
+++ b/drivers/hsi/clients/ssi_protocol.c
@@ -401,6 +401,7 @@ static void ssip_reset(struct hsi_client *cl)
 	del_timer(&ssi->rx_wd);
 	del_timer(&ssi->tx_wd);
 	del_timer(&ssi->keep_alive);
+	cancel_work_sync(&ssi->work);
 	ssi->main_state = 0;
 	ssi->send_state = 0;
 	ssi->recv_state = 0;
-- 
2.39.1.windows.1

Re:[PATCH v3] HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition

[Kaixin Wang]

At 2024-09-18 20:07:50, "Kaixin Wang" <kxwang23@m.fudan.edu.cn> wrote:
>In the ssi_protocol_probe() function, &ssi->work is bound with
>ssip_xmit_work(), In ssip_pn_setup(), the ssip_pn_xmit() function
>within the ssip_pn_ops structure is capable of starting the
>work.
>
>If we remove the module which will call ssi_protocol_remove()
>to make a cleanup, it will free ssi through kfree(ssi),
>while the work mentioned above will be used. The sequence
>of operations that may lead to a UAF bug is as follows:
>
>CPU0                                    CPU1
>
>                        | ssip_xmit_work
>ssi_protocol_remove     |
>kfree(ssi);             |
>                        | struct hsi_client *cl = ssi->cl;
>                        | // use ssi
>
>Fix it by ensuring that the work is canceled before proceeding
>with the cleanup in ssi_protocol_remove().
>
>Signed-off-by: Kaixin Wang <kxwang23@m.fudan.edu.cn>
>Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>
>---
>v3:
>- refer to the functions in the form of func() in the description message.
>- Link to v2: https://lore.kernel.org/r/20240914172142.328-1-kxwang23@m.fudan.edu.cn
>v2:
>- cancel the work in ssip_reset(), suggested by Sebastian
>- add the Acked-by label from Andy
>- Link to v1: https://lore.kernel.org/r/20240911151915.844957-1-kxwang23@m.fudan.edu.cn
>---
> drivers/hsi/clients/ssi_protocol.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/drivers/hsi/clients/ssi_protocol.c b/drivers/hsi/clients/ssi_protocol.c
>index afe470f3661c..6105ea9a6c6a 100644
>--- a/drivers/hsi/clients/ssi_protocol.c
>+++ b/drivers/hsi/clients/ssi_protocol.c
>@@ -401,6 +401,7 @@ static void ssip_reset(struct hsi_client *cl)
> 	del_timer(&ssi->rx_wd);
> 	del_timer(&ssi->tx_wd);
> 	del_timer(&ssi->keep_alive);
>+	cancel_work_sync(&ssi->work);
> 	ssi->main_state = 0;
> 	ssi->send_state = 0;
> 	ssi->recv_state = 0;
>-- 
>2.39.1.windows.1

>
Hi, I noticed that there are no relevant replies to this patch that I sent several months ago. Is it missed?

Re: [PATCH v3] HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition

[Andy Shevchenko]

On Mon, Feb 24, 2025 at 11:23:06AM +0800, Kaixin Wang wrote:
> At 2024-09-18 20:07:50, "Kaixin Wang" <kxwang23@m.fudan.edu.cn> wrote:

> >In the ssi_protocol_probe() function, &ssi->work is bound with
> >ssip_xmit_work(), In ssip_pn_setup(), the ssip_pn_xmit() function
> >within the ssip_pn_ops structure is capable of starting the
> >work.
> >
> >If we remove the module which will call ssi_protocol_remove()
> >to make a cleanup, it will free ssi through kfree(ssi),
> >while the work mentioned above will be used. The sequence
> >of operations that may lead to a UAF bug is as follows:
> >
> >CPU0                                    CPU1
> >
> >                        | ssip_xmit_work
> >ssi_protocol_remove     |
> >kfree(ssi);             |
> >                        | struct hsi_client *cl = ssi->cl;
> >                        | // use ssi
> >
> >Fix it by ensuring that the work is canceled before proceeding
> >with the cleanup in ssi_protocol_remove().

...

> Hi, I noticed that there are no relevant replies to this patch that I sent
> several months ago. Is it missed?

Seems like fell into cracks...

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3] HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition

[Sebastian Reichel]

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Hi,

On Mon, Feb 24, 2025 at 12:59:49PM +0200, Andy Shevchenko wrote:
> On Mon, Feb 24, 2025 at 11:23:06AM +0800, Kaixin Wang wrote:
> > At 2024-09-18 20:07:50, "Kaixin Wang" <kxwang23@m.fudan.edu.cn> wrote:
> 
> > >In the ssi_protocol_probe() function, &ssi->work is bound with
> > >ssip_xmit_work(), In ssip_pn_setup(), the ssip_pn_xmit() function
> > >within the ssip_pn_ops structure is capable of starting the
> > >work.
> > >
> > >If we remove the module which will call ssi_protocol_remove()
> > >to make a cleanup, it will free ssi through kfree(ssi),
> > >while the work mentioned above will be used. The sequence
> > >of operations that may lead to a UAF bug is as follows:
> > >
> > >CPU0                                    CPU1
> > >
> > >                        | ssip_xmit_work
> > >ssi_protocol_remove     |
> > >kfree(ssi);             |
> > >                        | struct hsi_client *cl = ssi->cl;
> > >                        | // use ssi
> > >
> > >Fix it by ensuring that the work is canceled before proceeding
> > >with the cleanup in ssi_protocol_remove().
> 
> ...
> 
> > Hi, I noticed that there are no relevant replies to this patch that I sent
> > several months ago. Is it missed?
> 
> Seems like fell into cracks...

Indeed, but queued to hsi for-next now.

-- Sebastian

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