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Message-ID: <d174e5cf-402d-48a0-b077-89740b873b73@google.com>
Date: Tue, 7 May 2024 14:02:35 -0700
From: Amit Sunil Dhamne <amitsd@...gle.com>
To: Ondřej Jirman <megi@....cz>, linux@...ck-us.net,
heikki.krogerus@...ux.intel.com, gregkh@...uxfoundation.org,
badhri@...gle.com, rdbabiera@...gle.com, linux-usb@...r.kernel.org,
stable@...r.kernel.org, linux-kernel@...r.kernel.org,
Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v1] usb: typec: tcpm: unregister existing source caps
before re-registration
Hi Ondřej,
On 5/7/24 09:19, Ondřej Jirman wrote:
> 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@...r.kernel.org
>> Cc: stable@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> Cc: Mark Brown <broonie@...nel.org>
>> Signed-off-by: Amit Sunil Dhamne <amitsd@...gle.com>
>> ---
>> 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.
Makes sense. I will send a fix for this. Thanks for the review.
Thanks,
Amit
>
> Kind regards,
> o.
>
>> base-commit: 0d31ea587709216d88183fe4ca0c8aba5e0205b8
>> --
>> 2.44.0.769.g3c40516874-goog
>>
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