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From: Jakub Sitnicki <jakub@cloudflare.com>
To: Martin Lau <kafai@fb.com>
Cc: "bpf\@vger.kernel.org" <bpf@vger.kernel.org>,
	"netdev\@vger.kernel.org" <netdev@vger.kernel.org>,
	"kernel-team\@cloudflare.com" <kernel-team@cloudflare.com>,
	Eric Dumazet <edumazet@google.com>,
	"John Fastabend" <john.fastabend@gmail.com>,
	Lorenz Bauer <lmb@cloudflare.com>
Subject: Re: [PATCH bpf-next v2 03/11] net, sk_msg: Clear sk_user_data pointer on clone if tagged
Date: Tue, 14 Jan 2020 17:04:33 +0100	[thread overview]
Message-ID: <87a76qrpm6.fsf@cloudflare.com> (raw)
In-Reply-To: <20200113201456.t5apbcjdqdr6by5t@kafai-mbp.dhcp.thefacebook.com>

On Mon, Jan 13, 2020 at 09:15 PM CET, Martin Lau wrote:
> On Fri, Jan 10, 2020 at 11:50:19AM +0100, Jakub Sitnicki wrote:
>> sk_user_data can hold a pointer to an object that is not intended to be
>> shared between the parent socket and the child that gets a pointer copy on
>> clone. This is the case when sk_user_data points at reference-counted
>> object, like struct sk_psock.
>> 
>> One way to resolve it is to tag the pointer with a no-copy flag by
>> repurposing its lowest bit. Based on the bit-flag value we clear the child
>> sk_user_data pointer after cloning the parent socket.
> LGTM.  One nit, WARN_ON_ONCE should be enough for all the cases if they
> would ever happen.  Having continuous splat on the same thing is not
> necessary useful while it could be quite distributing for people
> capture/log them.

Will switch to WARN_ON_ONCE in v3. Thanks for the review!

>
> Acked-by: Martin KaFai Lau <kafai@fb.com>


  reply	other threads:[~2020-01-14 16:04 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 10:50 [PATCH bpf-next v2 00/11] Extend SOCKMAP to store listening sockets Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 01/11] bpf, sk_msg: Don't reset saved sock proto on restore Jakub Sitnicki
2020-01-11 22:50   ` John Fastabend
2020-01-10 10:50 ` [PATCH bpf-next v2 02/11] net, sk_msg: Annotate lockless access to sk_prot on clone Jakub Sitnicki
2020-01-11 23:14   ` John Fastabend
2020-01-13 15:09     ` Jakub Sitnicki
2020-01-14  3:14       ` John Fastabend
2020-01-20 17:00       ` John Fastabend
2020-01-20 18:11         ` Jakub Sitnicki
2020-01-21 12:42           ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 03/11] net, sk_msg: Clear sk_user_data pointer on clone if tagged Jakub Sitnicki
2020-01-11 23:38   ` John Fastabend
2020-01-12 12:55   ` kbuild test robot
2020-01-13 20:15   ` Martin Lau
2020-01-14 16:04     ` Jakub Sitnicki [this message]
2020-01-10 10:50 ` [PATCH bpf-next v2 04/11] tcp_bpf: Don't let child socket inherit parent protocol ops on copy Jakub Sitnicki
2020-01-11  2:42   ` kbuild test robot
2020-01-11  3:02   ` kbuild test robot
2020-01-11 23:48   ` John Fastabend
2020-01-13 22:31     ` Jakub Sitnicki
2020-01-13 22:23   ` Martin Lau
2020-01-13 22:42     ` Jakub Sitnicki
2020-01-13 23:23       ` Martin Lau
2020-01-10 10:50 ` [PATCH bpf-next v2 05/11] bpf, sockmap: Allow inserting listening TCP sockets into sockmap Jakub Sitnicki
2020-01-11 23:59   ` John Fastabend
2020-01-13 15:48     ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 06/11] bpf, sockmap: Don't set up sockmap progs for listening sockets Jakub Sitnicki
2020-01-12  0:51   ` John Fastabend
2020-01-12  1:07     ` John Fastabend
2020-01-13 17:59       ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 07/11] bpf, sockmap: Return socket cookie on lookup from syscall Jakub Sitnicki
2020-01-12  0:56   ` John Fastabend
2020-01-13 23:12   ` Martin Lau
2020-01-14  3:16     ` John Fastabend
2020-01-14 15:48       ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 08/11] bpf, sockmap: Let all kernel-land lookup values in SOCKMAP Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 09/11] bpf: Allow selecting reuseport socket from a SOCKMAP Jakub Sitnicki
2020-01-12  1:00   ` John Fastabend
2020-01-13 23:45   ` Martin Lau
2020-01-15 12:41     ` Jakub Sitnicki
2020-01-13 23:51   ` Martin Lau
2020-01-15 12:57     ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 10/11] selftests/bpf: Extend SK_REUSEPORT tests to cover SOCKMAP Jakub Sitnicki
2020-01-12  1:01   ` John Fastabend
2020-01-10 10:50 ` [PATCH bpf-next v2 11/11] selftests/bpf: Tests for SOCKMAP holding listening sockets Jakub Sitnicki
2020-01-12  1:06   ` John Fastabend
2020-01-13 15:58     ` Jakub Sitnicki
2020-01-11  0:18 ` [PATCH bpf-next v2 00/11] Extend SOCKMAP to store " Alexei Starovoitov
2020-01-11 22:47 ` John Fastabend

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