linux-kernel - Re: [PATCH v2] posix-clock: posix-clock: Fix unbalanced locking in pc_clock

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Message-ID: <3afb4ea2-88d7-4099-9e53-e82416b7f35c@redhat.com>
Date: Wed, 23 Oct 2024 16:21:33 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Thomas Gleixner <tglx@...utronix.de>, Jinjie Ruan
 <ruanjinjie@...wei.com>, anna-maria@...utronix.de, frederic@...nel.org,
 kuba@...nel.org, richardcochran@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] posix-clock: posix-clock: Fix unbalanced locking in
 pc_clock_settime()

On 10/22/24 17:42, Paolo Abeni wrote:
> On 10/19/24 01:26, Thomas Gleixner wrote:
>> On Fri, Oct 18 2024 at 18:07, Jinjie Ruan wrote:
>>  If get_clock_desc() succeeds, it calls fget() for the clockid's fd,
>>> and get the clk->rwsem read lock, so the error path should release
>>> the lock to make the lock balance and fput the clockid's fd to make
>>> the refcount balance and release the fd related reosurce.
>>>
>>> However the below commit left the error path locked behind resulting in
>>> unbalanced locking. Check timespec64_valid_strict() before
>>> get_clock_desc() to fix it, because the "ts" is not changed
>>> after that.
>>>
>>> Fixes: d8794ac20a29 ("posix-clock: Fix missing timespec64 check in
>>> pc_clock_settime()")
>>
>> Jakub, I expect _you_ are going to pick this up and explain to Linus and
>> the stable people why we need a fix for the rushed in "fix".
> 
> I'm sorry, I noticed this patch right now thanks to Anna-Maria head-up
> on netdev.
> I'll merge it into net before this week PR.
> 
> Again, I'm sorry for this mess.

The patch is now merged into the 'net' tree:

https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=6e62807c7fbb3c758d233018caf94dfea9c65dbd

and I'll send it to Linus with tomorrow PR.

I forgot to mention Jakub could not reply as he is off-the-grid for a
few more days.

Cheers,

Paolo