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Date: Thu, 7 May 2026 11:38:05 +0100
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Subject: Re: [PATCH net] net: ena: PHC: Check return code before setting
 timestamp output
To: Arthur Kiyanovski <akiyano@amazon.com>, David Miller
 <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>,
 netdev@vger.kernel.org
Cc: Richard Cochran <richardcochran@gmail.com>,
 Eric Dumazet <edumazet@google.com>, Paolo Abeni <pabeni@redhat.com>,
 David Woodhouse <dwmw2@infradead.org>, Thomas Gleixner <tglx@linutronix.de>,
 Miroslav Lichvar <mlichvar@redhat.com>, Andrew Lunn <andrew+netdev@lunn.ch>,
 Wen Gu <guwen@linux.alibaba.com>, Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
 David Woodhouse <dwmw@amazon.com>, Yonatan Sarna <ysarna@amazon.com>,
 Zorik Machulsky <zorik@amazon.com>, Alexander Matushevsky
 <matua@amazon.com>, Saeed Bshara <saeedb@amazon.com>,
 Matt Wilson <msw@amazon.com>, Anthony Liguori <aliguori@amazon.com>,
 Nafea Bshara <nafea@amazon.com>, Evgeny Schmeilin <evgenys@amazon.com>,
 Netanel Belgazal <netanel@amazon.com>, Ali Saidi <alisaidi@amazon.com>,
 Benjamin Herrenschmidt <benh@amazon.com>, Noam Dagan <ndagan@amazon.com>,
 David Arinzon <darinzon@amazon.com>, Evgeny Ostrovsky <evostrov@amazon.com>,
 Ofir Tabachnik <ofirt@amazon.com>, Amit Bernstein <amitbern@amazon.com>,
 stable@vger.kernel.org
References: <20260507003518.22554-1-akiyano@amazon.com>
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From: Vadim Fedorenko <vadim.fedorenko@linux.dev>
In-Reply-To: <20260507003518.22554-1-akiyano@amazon.com>
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On 07/05/2026 01:35, Arthur Kiyanovski wrote:
> ena_phc_gettimex64() is setting the output parameter regardless
> of whether ena_com_phc_get_timestamp() succeeded or failed.
> 
> When ena_com_phc_get_timestamp() returns an error, the timestamp
> parameter may contain uninitialized stack memory (e.g., when PHC is
> disabled or in blocked state) or invalid hardware values. Passing
> these to userspace via the PTP ioctl is both a security issue
> (information leak) and a correctness bug.
> 
> Fix by checking the return code after releasing the lock and only
> setting the output timestamp on success.
> 
> Fixes: e0ea34158ee8 ("net: ena: Add PHC support in the ENA driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
> ---
>   drivers/net/ethernet/amazon/ena/ena_phc.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amazon/ena/ena_phc.c b/drivers/net/ethernet/amazon/ena/ena_phc.c
> index 7867e893fd15..c2a3ff1ef645 100644
> --- a/drivers/net/ethernet/amazon/ena/ena_phc.c
> +++ b/drivers/net/ethernet/amazon/ena/ena_phc.c
> @@ -46,9 +46,12 @@ static int ena_phc_gettimex64(struct ptp_clock_info *clock_info,
>   
>   	spin_unlock_irqrestore(&phc_info->lock, flags);
>   
> +	if (rc)
> +		return rc;
> +
>   	*ts = ns_to_timespec64(timestamp_nsec);
>   
> -	return rc;
> +	return 0;
>   }

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>

Just an observation while reviewing - the idea of taking 2 spinlocks
while reading timestamp doesn't look great and can potentially be
CPU-expensive. Please, consider refactoring into RCU-style...