On Wed, Apr 24, 2024 at 03:32:16PM GMT, Amit Sunil Dhamne wrote:
> Check and unregister existing source caps in tcpm_register_source_caps
> function before registering new ones. This change fixes following
> warning when port partner resends source caps after negotiating PD contract
> for the purpose of re-negotiation.
>
> [ 343.135030][ T151] sysfs: cannot create duplicate filename '/devices/virtual/usb_power_delivery/pd1/source-capabilities'
> [ 343.135071][ T151] Call trace:
> [ 343.135076][ T151] dump_backtrace+0xe8/0x108
> [ 343.135099][ T151] show_stack+0x18/0x24
> [ 343.135106][ T151] dump_stack_lvl+0x50/0x6c
> [ 343.135119][ T151] dump_stack+0x18/0x24
> [ 343.135126][ T151] sysfs_create_dir_ns+0xe0/0x140
> [ 343.135137][ T151] kobject_add_internal+0x228/0x424
> [ 343.135146][ T151] kobject_add+0x94/0x10c
> [ 343.135152][ T151] device_add+0x1b0/0x4c0
> [ 343.135187][ T151] device_register+0x20/0x34
> [ 343.135195][ T151] usb_power_delivery_register_capabilities+0x90/0x20c
> [ 343.135209][ T151] tcpm_pd_rx_handler+0x9f0/0x15b8
> [ 343.135216][ T151] kthread_worker_fn+0x11c/0x260
> [ 343.135227][ T151] kthread+0x114/0x1bc
> [ 343.135235][ T151] ret_from_fork+0x10/0x20
> [ 343.135265][ T151] kobject: kobject_add_internal failed for source-capabilities with -EEXIST, don't try to register things with the same name in the same directory.
>
> Fixes: 8203d26905ee ("usb: typec: tcpm: Register USB Power Delivery Capabilities")
> Cc: linux-usb@xxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Mark Brown <broonie@xxxxxxxxxx>
> Signed-off-by: Amit Sunil Dhamne <amitsd@xxxxxxxxxx>
> ---
> drivers/usb/typec/tcpm/tcpm.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index ab6ed6111ed0..d8eb89f4f0c3 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -2996,7 +2996,7 @@ static int tcpm_register_source_caps(struct tcpm_port *port)
> {
> struct usb_power_delivery_desc desc = { port->negotiated_rev };
> struct usb_power_delivery_capabilities_desc caps = { };
> - struct usb_power_delivery_capabilities *cap;
> + struct usb_power_delivery_capabilities *cap = port->partner_source_caps;
>
> if (!port->partner_pd)
> port->partner_pd = usb_power_delivery_register(NULL, &desc);
> @@ -3006,6 +3006,9 @@ static int tcpm_register_source_caps(struct tcpm_port *port)
> memcpy(caps.pdo, port->source_caps, sizeof(u32) * port->nr_source_caps);
> caps.role = TYPEC_SOURCE;
>
> + if (cap)
> + usb_power_delivery_unregister_capabilities(cap);
This certainly looks like it's asking for use after free on port->partner_source_caps
later on, since you're not clearing the pointer for the data that you just freed.
> +
> cap = usb_power_delivery_register_capabilities(port->partner_pd, &caps);
> if (IS_ERR(cap))
> return PTR_ERR(cap);
This can easily fail if caps contain invalid PDOs, resulting in keeping pointer
to freed memory in port->partner_source_caps.
Kind regards,
o.
> base-commit: 0d31ea587709216d88183fe4ca0c8aba5e0205b8
> --
> 2.44.0.769.g3c40516874-goog
>
