From: Jakub Sitnicki <jakub@cloudflare.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org, kernel-team@cloudflare.com,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Haowei Yan <g1042620637@gmail.com>,
Tom Parkin <tparkin@katalix.com>
Subject: Re: [PATCH net v2] l2tp: Serialize access to sk_user_data with sock lock
Date: Wed, 17 Aug 2022 16:33:33 +0200 [thread overview]
Message-ID: <87edxfvsxs.fsf@cloudflare.com> (raw)
In-Reply-To: <20220816184150.78d6e3e3@kernel.org>
On Tue, Aug 16, 2022 at 06:41 PM -07, Jakub Kicinski wrote:
> On Mon, 15 Aug 2022 15:01:07 +0200 Jakub Sitnicki wrote:
>> sk->sk_user_data has multiple users, which are not compatible with each
>> other. To synchronize the users, any check-if-unused-and-set access to the
>> pointer has to happen with sock lock held.
>>
>> l2tp currently fails to grab the lock when modifying the underlying tunnel
>> socket. Fix it by adding appropriate locking.
>>
>> We don't to grab the lock when l2tp clears sk_user_data, because it happens
>> only in sk->sk_destruct, when the sock is going away.
>
> Note to other netdev maintainers that based on the discussion about
> the reuseport locking it's unclear whether we shouldn't also take
> the callback lock...
You're right. reuseport_array, psock, and kcm protect sk_user_data with
the callback lock, not the sock lock. Need to fix it.
next prev parent reply other threads:[~2022-08-17 14:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-15 13:01 [PATCH net v2] l2tp: Serialize access to sk_user_data with sock lock Jakub Sitnicki
2022-08-15 13:21 ` Tom Parkin
2022-08-15 13:26 ` Jakub Sitnicki
2022-08-15 13:39 ` Tom Parkin
2022-08-17 1:41 ` Jakub Kicinski
2022-08-17 14:33 ` Jakub Sitnicki [this message]
2022-08-17 15:51 ` Jakub Kicinski
2022-08-17 15:56 ` Jakub Sitnicki
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