Received-SPF: pass (google.com: domain of linux-kernel+bounces-141326-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <813d33ec-a462-48a9-b2f3-d890969dca1b@kernel.dk>
Date: Thu, 11 Apr 2024 10:32:12 -0600
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 2/4] timerfd: convert to ->read_iter()
Content-Language: en-US
To: Marek Szyprowski <m.szyprowski@samsung.com>, linux-fsdevel@vger.kernel.org
Cc: brauner@kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
References: <20240409152438.77960-1-axboe@kernel.dk>
 <20240409152438.77960-3-axboe@kernel.dk>
 <1a1c00fb-c83f-44e7-bc6a-cfe52d780c35@kernel.dk>
 <CGME20240411114048eucas1p21707a2d0bfb9c5a21f3e8aa76c0d82c1@eucas1p2.samsung.com>
 <528e184b-9cb1-40a7-b757-db11a852dd59@samsung.com>
From: Jens Axboe <axboe@kernel.dk>
In-Reply-To: <528e184b-9cb1-40a7-b757-db11a852dd59@samsung.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

On 4/11/24 5:40 AM, Marek Szyprowski wrote:
> Hi,
> 
> On 11.04.2024 00:27, Jens Axboe wrote:
>> On 4/9/24 9:22 AM, Jens Axboe wrote:
>>> @@ -312,8 +313,8 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
>>>   		ctx->ticks = 0;
>>>   	}
>>>   	spin_unlock_irq(&ctx->wqh.lock);
>>> -	if (ticks)
>>> -		res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks);
>>> +	if (ticks && !copy_to_iter_full(&ticks, sizeof(ticks), to))
>>> +		res = -EFAULT;
>>>   	return res;
>>>   }
>> Dumb thinko here, as that should be:
>>
>> if (ticks) {
>> 	res = copy_to_iter(&ticks, sizeof(ticks), to);
>> 	if (!res)
>> 		res = -EFAULT;
>> }
>>
>> I've updated my branch, just a heads-up. Odd how it passing testing,
>> guess I got stack lucky...
> 
> The old version got its way into today's linux-next and bisecting the 
> boot issues directed me here. There is nothing more to report, but I can 
> confirm that the above change indeed fixes the problems observed on 
> next-20240411.

Yeah sorry about that :(

> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

Thanks!

> I hope that tomorrow's linux-next will have the correct version of this 
> patch.

It should, the branches have been updated.

-- 
Jens Axboe