| Message ID | 20240427175010.3367154-1-badhri@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v1] usb: typec: tcpm: Check for port partner validity before consuming it | expand |
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 >
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;
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(-) base-commit: 3f12222a4bebeb13ce06ddecc1610ad32fa835dd