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Date: Thu, 4 Apr 2024 15:22:35 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Kyle Tso <kyletso@google.com>
Cc: linux@roeck-us.net, heikki.krogerus@linux.intel.com, badhri@google.com,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] usb: typec: tcpm: Correct the PDO counting in pd_set
Message-ID: <2024040417-ice-decal-b37e@gregkh>
References: <20240326151909.440275-1-kyletso@google.com>
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In-Reply-To: <20240326151909.440275-1-kyletso@google.com>

On Tue, Mar 26, 2024 at 11:19:09PM +0800, Kyle Tso wrote:
> Off-by-one errors happen because nr_snk_pdo and nr_src_pdo are
> incorrectly added one. The index of the loop is equal to the number of
> PDOs to be updated when leaving the loop and it doesn't need to be added
> one.
> 
> When doing the power negotiation, TCPM relies on the "nr_snk_pdo" as
> the size of the local sink PDO array to match the Source capabilities
> of the partner port. If the off-by-one overflow occurs, a wrong RDO
> might be sent and unexpected power transfer might happen such as over
> voltage or over current (than expected).
> 
> "nr_src_pdo" is used to set the Rp level when the port is in Source
> role. It is also the array size of the local Source capabilities when
> filling up the buffer which will be sent as the Source PDOs (such as
> in Power Negotiation). If the off-by-one overflow occurs, a wrong Rp
> level might be set and wrong Source PDOs will be sent to the partner
> port. This could potentially cause over current or port resets.
> 
> Fixes: cd099cde4ed2 ("usb: typec: tcpm: Support multiple capabilities")
> Cc: stable@vger.kernel.org
> Signed-off-by: Kyle Tso <kyletso@google.com>
> ---
> v1 -> v2:
> - update the commit message (adding the problems this patch solves)
> 
>  drivers/usb/typec/tcpm/tcpm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

This fails to apply to my usb-linus branch :(

Can you rebase and resend?

thanks,

greg k-h