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[PATCH v1] usb: typec: tcpm: Check for port partner validity before consuming it

Badhri Jagan Sridharan posted 1 patch 1 year, 7 months ago
There is a newer version of this series
drivers/usb/typec/tcpm/tcpm.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
[PATCH v1] usb: typec: tcpm: Check for port partner validity before consuming it
Posted by Badhri Jagan Sridharan 1 year, 7 months ago 
typec_register_partner() does not guarantee partner registration
to always succeed. In the event of failure, port->partner is set
to the error value or NULL. Given that port->partner validity is
not checked, this results in the following crash:

[17514.377076][  T275] Unable to handle kernel NULL pointer dereference at virtual address 00000000000003c0
[17514.378270][  T275] pc : run_state_machine+0x1bc8/0x1c08
[17514.378286][  T275] lr : run_state_machine+0x1b90/0x1c08
..
[17514.378377][  T275] Call trace:
[17514.378381][  T275]  run_state_machine+0x1bc8/0x1c08
[17514.378388][  T275]  tcpm_state_machine_work+0x94/0xe4
[17514.378396][  T275]  kthread_worker_fn+0x118/0x328
[17514.378406][  T275]  kthread+0x1d0/0x23c
[17514.378412][  T275]  ret_from_fork+0x10/0x20

To prevent the crash, check for port->partner validity before
derefencing it in all the call sites.

Cc: stable@vger.kernel.org
Fixes: c97cd0b4b54e ("usb: typec: tcpm: set initial svdm version based on pd revision")
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
---
 drivers/usb/typec/tcpm/tcpm.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index ab6ed6111ed0..8a4fa8d875c6 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -4,7 +4,6 @@
  *
  * USB Power Delivery protocol stack.
  */
-
 #include <linux/completion.h>
 #include <linux/debugfs.h>
 #include <linux/device.h>
@@ -1580,7 +1579,8 @@ static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt)
 	port->partner_ident.cert_stat = p[VDO_INDEX_CSTAT];
 	port->partner_ident.product = product;
 
-	typec_partner_set_identity(port->partner);
+	if (!IS_ERR_OR_NULL(port->partner))
+		typec_partner_set_identity(port->partner);
 
 	tcpm_log(port, "Identity: %04x:%04x.%04x",
 		 PD_IDH_VID(vdo),
@@ -1742,6 +1742,9 @@ static void tcpm_register_partner_altmodes(struct tcpm_port *port)
 	struct typec_altmode *altmode;
 	int i;
 
+	if (IS_ERR_OR_NULL(port->partner))
+		return;
+
 	for (i = 0; i < modep->altmodes; i++) {
 		altmode = typec_partner_register_altmode(port->partner,
 						&modep->altmode_desc[i]);
@@ -4244,7 +4247,8 @@ static void tcpm_typec_connect(struct tcpm_port *port)
 		port->partner = typec_register_partner(port->typec_port,
 						       &port->partner_desc);
 		port->connected = true;
-		typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
+		if (!IS_ERR_OR_NULL(port->partner))
+			typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
 	}
 }
 
@@ -4323,8 +4327,10 @@ static void tcpm_typec_disconnect(struct tcpm_port *port)
 	port->plug_prime = NULL;
 	port->cable = NULL;
 	if (port->connected) {
-		typec_partner_set_usb_power_delivery(port->partner, NULL);
-		typec_unregister_partner(port->partner);
+		if (!IS_ERR_OR_NULL(port->partner)) {
+			typec_partner_set_usb_power_delivery(port->partner, NULL);
+			typec_unregister_partner(port->partner);
+		}
 		port->partner = NULL;
 		port->connected = false;
 	}
@@ -4549,6 +4555,9 @@ static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
 
 static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
 {
+	if (IS_ERR_OR_NULL(port->partner))
+		return;
+
 	switch (port->negotiated_rev) {
 	case PD_REV30:
 		break;

base-commit: 3f12222a4bebeb13ce06ddecc1610ad32fa835dd
-- 
2.44.0.769.g3c40516874-goog
Re: [PATCH v1] usb: typec: tcpm: Check for port partner validity before consuming it
Posted by Dmitry Baryshkov 1 year, 7 months ago 
On Sat, Apr 27, 2024 at 05:50:10PM +0000, Badhri Jagan Sridharan wrote:
> typec_register_partner() does not guarantee partner registration
> to always succeed. In the event of failure, port->partner is set
> to the error value or NULL. Given that port->partner validity is
> not checked, this results in the following crash:
> 
> [17514.377076][  T275] Unable to handle kernel NULL pointer dereference at virtual address 00000000000003c0
> [17514.378270][  T275] pc : run_state_machine+0x1bc8/0x1c08
> [17514.378286][  T275] lr : run_state_machine+0x1b90/0x1c08
> ..
> [17514.378377][  T275] Call trace:
> [17514.378381][  T275]  run_state_machine+0x1bc8/0x1c08
> [17514.378388][  T275]  tcpm_state_machine_work+0x94/0xe4
> [17514.378396][  T275]  kthread_worker_fn+0x118/0x328
> [17514.378406][  T275]  kthread+0x1d0/0x23c
> [17514.378412][  T275]  ret_from_fork+0x10/0x20

Nit: thre is little use in the timestamps and the T275 tag. In future
patches you can safely ommit such data.

> 
> To prevent the crash, check for port->partner validity before
> derefencing it in all the call sites.
> 
> Cc: stable@vger.kernel.org
> Fixes: c97cd0b4b54e ("usb: typec: tcpm: set initial svdm version based on pd revision")
> Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index ab6ed6111ed0..8a4fa8d875c6 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4,7 +4,6 @@
>   *
>   * USB Power Delivery protocol stack.
>   */
> -
>  #include <linux/completion.h>
>  #include <linux/debugfs.h>
>  #include <linux/device.h>
> @@ -1580,7 +1579,8 @@ static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt)
>  	port->partner_ident.cert_stat = p[VDO_INDEX_CSTAT];
>  	port->partner_ident.product = product;
>  
> -	typec_partner_set_identity(port->partner);
> +	if (!IS_ERR_OR_NULL(port->partner))

I think that it might be better to check typec_register_partner() result
in tcpm_typec_connect() and skip setting port->partner in case it
returned an error (an error message would be also beneficial).
See for example, how this is handled in ucsi_register_partner().

Then these checks can be turned into simple `if (port->partner)`.

> +		typec_partner_set_identity(port->partner);
>  
>  	tcpm_log(port, "Identity: %04x:%04x.%04x",
>  		 PD_IDH_VID(vdo),
> @@ -1742,6 +1742,9 @@ static void tcpm_register_partner_altmodes(struct tcpm_port *port)
>  	struct typec_altmode *altmode;
>  	int i;
>  
> +	if (IS_ERR_OR_NULL(port->partner))
> +		return;
> +
>  	for (i = 0; i < modep->altmodes; i++) {
>  		altmode = typec_partner_register_altmode(port->partner,
>  						&modep->altmode_desc[i]);
> @@ -4244,7 +4247,8 @@ static void tcpm_typec_connect(struct tcpm_port *port)
>  		port->partner = typec_register_partner(port->typec_port,
>  						       &port->partner_desc);
>  		port->connected = true;
> -		typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
> +		if (!IS_ERR_OR_NULL(port->partner))
> +			typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
>  	}
>  }
>  
> @@ -4323,8 +4327,10 @@ static void tcpm_typec_disconnect(struct tcpm_port *port)
>  	port->plug_prime = NULL;
>  	port->cable = NULL;
>  	if (port->connected) {
> -		typec_partner_set_usb_power_delivery(port->partner, NULL);
> -		typec_unregister_partner(port->partner);
> +		if (!IS_ERR_OR_NULL(port->partner)) {
> +			typec_partner_set_usb_power_delivery(port->partner, NULL);
> +			typec_unregister_partner(port->partner);
> +		}
>  		port->partner = NULL;
>  		port->connected = false;
>  	}
> @@ -4549,6 +4555,9 @@ static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
>  
>  static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
>  {
> +	if (IS_ERR_OR_NULL(port->partner))
> +		return;
> +
>  	switch (port->negotiated_rev) {
>  	case PD_REV30:
>  		break;
> 
> base-commit: 3f12222a4bebeb13ce06ddecc1610ad32fa835dd
> -- 
> 2.44.0.769.g3c40516874-goog
> 

-- 
With best wishes
Dmitry
Re: [PATCH v1] usb: typec: tcpm: Check for port partner validity before consuming it
Posted by Badhri Jagan Sridharan 1 year, 7 months ago 
On Sat, Apr 27, 2024 at 12:23 PM Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> wrote:
>
> On Sat, Apr 27, 2024 at 05:50:10PM +0000, Badhri Jagan Sridharan wrote:
> > typec_register_partner() does not guarantee partner registration
> > to always succeed. In the event of failure, port->partner is set
> > to the error value or NULL. Given that port->partner validity is
> > not checked, this results in the following crash:
> >
> > [17514.377076][  T275] Unable to handle kernel NULL pointer dereference at virtual address 00000000000003c0
> > [17514.378270][  T275] pc : run_state_machine+0x1bc8/0x1c08
> > [17514.378286][  T275] lr : run_state_machine+0x1b90/0x1c08
> > ..
> > [17514.378377][  T275] Call trace:
> > [17514.378381][  T275]  run_state_machine+0x1bc8/0x1c08
> > [17514.378388][  T275]  tcpm_state_machine_work+0x94/0xe4
> > [17514.378396][  T275]  kthread_worker_fn+0x118/0x328
> > [17514.378406][  T275]  kthread+0x1d0/0x23c
> > [17514.378412][  T275]  ret_from_fork+0x10/0x20
>
> Nit: thre is little use in the timestamps and the T275 tag. In future
> patches you can safely ommit such data.
>
> >
> > To prevent the crash, check for port->partner validity before
> > derefencing it in all the call sites.
> >
> > Cc: stable@vger.kernel.org
> > Fixes: c97cd0b4b54e ("usb: typec: tcpm: set initial svdm version based on pd revision")
> > Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
> > ---
> >  drivers/usb/typec/tcpm/tcpm.c | 19 ++++++++++++++-----
> >  1 file changed, 14 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> > index ab6ed6111ed0..8a4fa8d875c6 100644
> > --- a/drivers/usb/typec/tcpm/tcpm.c
> > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > @@ -4,7 +4,6 @@
> >   *
> >   * USB Power Delivery protocol stack.
> >   */
> > -
> >  #include <linux/completion.h>
> >  #include <linux/debugfs.h>
> >  #include <linux/device.h>
> > @@ -1580,7 +1579,8 @@ static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt)
> >       port->partner_ident.cert_stat = p[VDO_INDEX_CSTAT];
> >       port->partner_ident.product = product;
> >
> > -     typec_partner_set_identity(port->partner);
> > +     if (!IS_ERR_OR_NULL(port->partner))
>
> I think that it might be better to check typec_register_partner() result
> in tcpm_typec_connect() and skip setting port->partner in case it
> returned an error (an error message would be also beneficial).
> See for example, how this is handled in ucsi_register_partner().
>
> Then these checks can be turned into simple `if (port->partner)`.


Sounds good ! However, I was wondering whether the error message is
redundant as typec_register_partner() also prints one. I have anyways
added that in V3.

Thanks,
Badhri

>
> > +             typec_partner_set_identity(port->partner);
> >
> >       tcpm_log(port, "Identity: %04x:%04x.%04x",
> >                PD_IDH_VID(vdo),
> > @@ -1742,6 +1742,9 @@ static void tcpm_register_partner_altmodes(struct tcpm_port *port)
> >       struct typec_altmode *altmode;
> >       int i;
> >
> > +     if (IS_ERR_OR_NULL(port->partner))
> > +             return;
> > +
> >       for (i = 0; i < modep->altmodes; i++) {
> >               altmode = typec_partner_register_altmode(port->partner,
> >                                               &modep->altmode_desc[i]);
> > @@ -4244,7 +4247,8 @@ static void tcpm_typec_connect(struct tcpm_port *port)
> >               port->partner = typec_register_partner(port->typec_port,
> >                                                      &port->partner_desc);
> >               port->connected = true;
> > -             typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
> > +             if (!IS_ERR_OR_NULL(port->partner))
> > +                     typec_partner_set_usb_power_delivery(port->partner, port->partner_pd);
> >       }
> >  }
> >
> > @@ -4323,8 +4327,10 @@ static void tcpm_typec_disconnect(struct tcpm_port *port)
> >       port->plug_prime = NULL;
> >       port->cable = NULL;
> >       if (port->connected) {
> > -             typec_partner_set_usb_power_delivery(port->partner, NULL);
> > -             typec_unregister_partner(port->partner);
> > +             if (!IS_ERR_OR_NULL(port->partner)) {
> > +                     typec_partner_set_usb_power_delivery(port->partner, NULL);
> > +                     typec_unregister_partner(port->partner);
> > +             }
> >               port->partner = NULL;
> >               port->connected = false;
> >       }
> > @@ -4549,6 +4555,9 @@ static enum typec_cc_status tcpm_pwr_opmode_to_rp(enum typec_pwr_opmode opmode)
> >
> >  static void tcpm_set_initial_svdm_version(struct tcpm_port *port)
> >  {
> > +     if (IS_ERR_OR_NULL(port->partner))
> > +             return;
> > +
> >       switch (port->negotiated_rev) {
> >       case PD_REV30:
> >               break;
> >
> > base-commit: 3f12222a4bebeb13ce06ddecc1610ad32fa835dd
> > --
> > 2.44.0.769.g3c40516874-goog
> >
>
> --
> With best wishes
> Dmitry

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