6.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: RD Babiera rdbabiera@google.com
commit 324d45e53f1a36c88bc649dc39e0c8300a41be0a upstream.
A state check was previously added to tcpm_queue_vdm_unlocked to prevent a deadlock where the DisplayPort Alt Mode driver would be executing work and attempting to grab the tcpm_lock while the TCPM was holding the lock and attempting to unregister the altmode, blocking on the altmode driver's cancel_work_sync call.
Because the state check isn't protected, there is a small window where the Alt Mode driver could determine that the TCPM is in a ready state and attempt to grab the lock while the TCPM grabs the lock and changes the TCPM state to one that causes the deadlock. The callstack is provided below:
[110121.667392][ C7] Call trace: [110121.667396][ C7] __switch_to+0x174/0x338 [110121.667406][ C7] __schedule+0x608/0x9f0 [110121.667414][ C7] schedule+0x7c/0xe8 [110121.667423][ C7] kernfs_drain+0xb0/0x114 [110121.667431][ C7] __kernfs_remove+0x16c/0x20c [110121.667436][ C7] kernfs_remove_by_name_ns+0x74/0xe8 [110121.667442][ C7] sysfs_remove_group+0x84/0xe8 [110121.667450][ C7] sysfs_remove_groups+0x34/0x58 [110121.667458][ C7] device_remove_groups+0x10/0x20 [110121.667464][ C7] device_release_driver_internal+0x164/0x2e4 [110121.667475][ C7] device_release_driver+0x18/0x28 [110121.667484][ C7] bus_remove_device+0xec/0x118 [110121.667491][ C7] device_del+0x1e8/0x4ac [110121.667498][ C7] device_unregister+0x18/0x38 [110121.667504][ C7] typec_unregister_altmode+0x30/0x44 [110121.667515][ C7] tcpm_reset_port+0xac/0x370 [110121.667523][ C7] tcpm_snk_detach+0x84/0xb8 [110121.667529][ C7] run_state_machine+0x4c0/0x1b68 [110121.667536][ C7] tcpm_state_machine_work+0x94/0xe4 [110121.667544][ C7] kthread_worker_fn+0x10c/0x244 [110121.667552][ C7] kthread+0x104/0x1d4 [110121.667557][ C7] ret_from_fork+0x10/0x20
[110121.667689][ C7] Workqueue: events dp_altmode_work [110121.667697][ C7] Call trace: [110121.667701][ C7] __switch_to+0x174/0x338 [110121.667710][ C7] __schedule+0x608/0x9f0 [110121.667717][ C7] schedule+0x7c/0xe8 [110121.667725][ C7] schedule_preempt_disabled+0x24/0x40 [110121.667733][ C7] __mutex_lock+0x408/0xdac [110121.667741][ C7] __mutex_lock_slowpath+0x14/0x24 [110121.667748][ C7] mutex_lock+0x40/0xec [110121.667757][ C7] tcpm_altmode_enter+0x78/0xb4 [110121.667764][ C7] typec_altmode_enter+0xdc/0x10c [110121.667769][ C7] dp_altmode_work+0x68/0x164 [110121.667775][ C7] process_one_work+0x1e4/0x43c [110121.667783][ C7] worker_thread+0x25c/0x430 [110121.667789][ C7] kthread+0x104/0x1d4 [110121.667794][ C7] ret_from_fork+0x10/0x20
Change tcpm_queue_vdm_unlocked to queue for tcpm_queue_vdm_work, which can perform the state check while holding the TCPM lock while the Alt Mode lock is no longer held. This requires a new struct to hold the vdm data, altmode_vdm_event.
Fixes: cdc9946ea637 ("usb: typec: tcpm: enforce ready state when queueing alt mode vdm") Cc: stable stable@kernel.org Signed-off-by: RD Babiera rdbabiera@google.com Reviewed-by: Heikki Krogerus heikki.krogerus@linux.intel.com Reviewed-by: Badhri Jagan Sridharan badhri@google.com Link: https://lore.kernel.org/r/20250506232853.1968304-2-rdbabiera@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/typec/tcpm/tcpm.c | 91 ++++++++++++++++++++++++++++++++---------- 1 file changed, 71 insertions(+), 20 deletions(-)
--- a/drivers/usb/typec/tcpm/tcpm.c +++ b/drivers/usb/typec/tcpm/tcpm.c @@ -596,6 +596,15 @@ struct pd_rx_event { enum tcpm_transmit_type rx_sop_type; };
+struct altmode_vdm_event { + struct kthread_work work; + struct tcpm_port *port; + u32 header; + u32 *data; + int cnt; + enum tcpm_transmit_type tx_sop_type; +}; + static const char * const pd_rev[] = { [PD_REV10] = "rev1", [PD_REV20] = "rev2", @@ -1608,18 +1617,68 @@ static void tcpm_queue_vdm(struct tcpm_p mod_vdm_delayed_work(port, 0); }
-static void tcpm_queue_vdm_unlocked(struct tcpm_port *port, const u32 header, - const u32 *data, int cnt, enum tcpm_transmit_type tx_sop_type) +static void tcpm_queue_vdm_work(struct kthread_work *work) { - if (port->state != SRC_READY && port->state != SNK_READY && - port->state != SRC_VDM_IDENTITY_REQUEST) - return; + struct altmode_vdm_event *event = container_of(work, + struct altmode_vdm_event, + work); + struct tcpm_port *port = event->port;
mutex_lock(&port->lock); - tcpm_queue_vdm(port, header, data, cnt, tx_sop_type); + if (port->state != SRC_READY && port->state != SNK_READY && + port->state != SRC_VDM_IDENTITY_REQUEST) { + tcpm_log_force(port, "dropping altmode_vdm_event"); + goto port_unlock; + } + + tcpm_queue_vdm(port, event->header, event->data, event->cnt, event->tx_sop_type); + +port_unlock: + kfree(event->data); + kfree(event); mutex_unlock(&port->lock); }
+static int tcpm_queue_vdm_unlocked(struct tcpm_port *port, const u32 header, + const u32 *data, int cnt, enum tcpm_transmit_type tx_sop_type) +{ + struct altmode_vdm_event *event; + u32 *data_cpy; + int ret = -ENOMEM; + + event = kzalloc(sizeof(*event), GFP_KERNEL); + if (!event) + goto err_event; + + data_cpy = kcalloc(cnt, sizeof(u32), GFP_KERNEL); + if (!data_cpy) + goto err_data; + + kthread_init_work(&event->work, tcpm_queue_vdm_work); + event->port = port; + event->header = header; + memcpy(data_cpy, data, sizeof(u32) * cnt); + event->data = data_cpy; + event->cnt = cnt; + event->tx_sop_type = tx_sop_type; + + ret = kthread_queue_work(port->wq, &event->work); + if (!ret) { + ret = -EBUSY; + goto err_queue; + } + + return 0; + +err_queue: + kfree(data_cpy); +err_data: + kfree(event); +err_event: + tcpm_log_force(port, "failed to queue altmode vdm, err:%d", ret); + return ret; +} + static void svdm_consume_identity(struct tcpm_port *port, const u32 *p, int cnt) { u32 vdo = p[VDO_INDEX_IDH]; @@ -2830,8 +2889,7 @@ static int tcpm_altmode_enter(struct typ header = VDO(altmode->svid, vdo ? 2 : 1, svdm_version, CMD_ENTER_MODE); header |= VDO_OPOS(altmode->mode);
- tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP); - return 0; + return tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP); }
static int tcpm_altmode_exit(struct typec_altmode *altmode) @@ -2847,8 +2905,7 @@ static int tcpm_altmode_exit(struct type header = VDO(altmode->svid, 1, svdm_version, CMD_EXIT_MODE); header |= VDO_OPOS(altmode->mode);
- tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP); - return 0; + return tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP); }
static int tcpm_altmode_vdm(struct typec_altmode *altmode, @@ -2856,9 +2913,7 @@ static int tcpm_altmode_vdm(struct typec { struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
- tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP); - - return 0; + return tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP); }
static const struct typec_altmode_ops tcpm_altmode_ops = { @@ -2882,8 +2937,7 @@ static int tcpm_cable_altmode_enter(stru header = VDO(altmode->svid, vdo ? 2 : 1, svdm_version, CMD_ENTER_MODE); header |= VDO_OPOS(altmode->mode);
- tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP_PRIME); - return 0; + return tcpm_queue_vdm_unlocked(port, header, vdo, vdo ? 1 : 0, TCPC_TX_SOP_PRIME); }
static int tcpm_cable_altmode_exit(struct typec_altmode *altmode, enum typec_plug_index sop) @@ -2899,8 +2953,7 @@ static int tcpm_cable_altmode_exit(struc header = VDO(altmode->svid, 1, svdm_version, CMD_EXIT_MODE); header |= VDO_OPOS(altmode->mode);
- tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP_PRIME); - return 0; + return tcpm_queue_vdm_unlocked(port, header, NULL, 0, TCPC_TX_SOP_PRIME); }
static int tcpm_cable_altmode_vdm(struct typec_altmode *altmode, enum typec_plug_index sop, @@ -2908,9 +2961,7 @@ static int tcpm_cable_altmode_vdm(struct { struct tcpm_port *port = typec_altmode_get_drvdata(altmode);
- tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP_PRIME); - - return 0; + return tcpm_queue_vdm_unlocked(port, header, data, count - 1, TCPC_TX_SOP_PRIME); }
static const struct typec_cable_ops tcpm_cable_ops = {