From 38e1f2ee82bacbbfded8f1c06794a443d038d054 Mon Sep 17 00:00:00 2001 From: RD Babiera Date: Mon, 14 Aug 2023 18:05:59 +0000 Subject: [PATCH] usb: typec: bus: verify partner exists in typec_altmode_attention commit f23643306430f86e2f413ee2b986e0773e79da31 upstream. Some usb hubs will negotiate DisplayPort Alt mode with the device but will then negotiate a data role swap after entering the alt mode. The data role swap causes the device to unregister all alt modes, however the usb hub will still send Attention messages even after failing to reregister the Alt Mode. type_altmode_attention currently does not verify whether or not a device's altmode partner exists, which results in a NULL pointer error when dereferencing the typec_altmode and typec_altmode_ops belonging to the altmode partner. Verify the presence of a device's altmode partner before sending the Attention message to the Alt Mode driver. Fixes: 8a37d87d72f0 ("usb: typec: Bus type for alternate modes") Cc: stable@vger.kernel.org Signed-off-by: RD Babiera Reviewed-by: Heikki Krogerus Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20230814180559.923475-1-rdbabiera@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/typec/bus.c | 12 ++++++++++-- drivers/usb/typec/tcpm/tcpm.c | 3 ++- include/linux/usb/typec_altmode.h | 2 +- 3 files changed, 13 insertions(+), 4 deletions(-) diff --git a/drivers/usb/typec/bus.c b/drivers/usb/typec/bus.c index f4e7f4d78b56..7994b46592b9 100644 --- a/drivers/usb/typec/bus.c +++ b/drivers/usb/typec/bus.c @@ -152,12 +152,20 @@ EXPORT_SYMBOL_GPL(typec_altmode_exit); * * Notifies the partner of @adev about Attention command. */ -void typec_altmode_attention(struct typec_altmode *adev, u32 vdo) +int typec_altmode_attention(struct typec_altmode *adev, u32 vdo) { - struct typec_altmode *pdev = &to_altmode(adev)->partner->adev; + struct altmode *partner = to_altmode(adev)->partner; + struct typec_altmode *pdev; + + if (!partner) + return -ENODEV; + + pdev = &partner->adev; if (pdev->ops && pdev->ops->attention) pdev->ops->attention(pdev, vdo); + + return 0; } EXPORT_SYMBOL_GPL(typec_altmode_attention); diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c index cf0e6a80815a..ac3953a0fa29 100644 --- a/drivers/usb/typec/tcpm/tcpm.c +++ b/drivers/usb/typec/tcpm/tcpm.c @@ -1395,7 +1395,8 @@ static void tcpm_handle_vdm_request(struct tcpm_port *port, } break; case ADEV_ATTENTION: - typec_altmode_attention(adev, p[1]); + if (typec_altmode_attention(adev, p[1])) + tcpm_log(port, "typec_altmode_attention no port partner altmode"); break; } } diff --git a/include/linux/usb/typec_altmode.h b/include/linux/usb/typec_altmode.h index 5e0a7b7647c3..22b8ee8f0311 100644 --- a/include/linux/usb/typec_altmode.h +++ b/include/linux/usb/typec_altmode.h @@ -67,7 +67,7 @@ struct typec_altmode_ops { int typec_altmode_enter(struct typec_altmode *altmode, u32 *vdo); int typec_altmode_exit(struct typec_altmode *altmode); -void typec_altmode_attention(struct typec_altmode *altmode, u32 vdo); +int typec_altmode_attention(struct typec_altmode *altmode, u32 vdo); int typec_altmode_vdm(struct typec_altmode *altmode, const u32 header, const u32 *vdo, int count); int typec_altmode_notify(struct typec_altmode *altmode, unsigned long conf,