From: Jakub Sitnicki <jakub@cloudflare.com>
To: Michal Luczaj <mhal@rbox.co>
Cc: sashiko-reviews@lists.linux.dev, bpf@vger.kernel.org
Subject: Re: [PATCH bpf v2 1/4] bpf, sockmap: Reject unhashed UDP sockets on sockmap update
Date: Mon, 29 Jun 2026 13:37:34 +0200 [thread overview]
Message-ID: <87v7b137cx.fsf@cloudflare.com> (raw)
In-Reply-To: <e08be4f5-0bd9-4228-843d-86ed20594bac@rbox.co> (Michal Luczaj's message of "Sun, 28 Jun 2026 23:59:37 +0200")
On Sun, Jun 28, 2026 at 11:59 PM +02, Michal Luczaj wrote:
> On 6/26/26 22:58, sashiko-bot@kernel.org wrote:
>> [Severity: High]
>> Could a memory ordering regression here allow unbound UDP sockets to still
>> bypass this check?
>>
>> In udp_v4_get_port(), the flag and hash are set:
>>
>> net/ipv4/udp.c:udp_v4_get_port() {
>> ...
>> sock_set_flag(sk, SOCK_RCU_FREE);
>> sk_add_node_rcu(sk, &hslot->head);
>> ...
>> }
>>
>> Because these stores lack a memory barrier between them, could sk_hashed(sk)
>> return true on another CPU while SOCK_RCU_FREE is not yet visible, allowing
>> the leak to still trigger?
>
> I'd like to verify it on a weakly-ordered CPU; please give me a day or two.
False positive, IMO.
Both ->get_port and sock_map_sk_state_allowed run with sk_lock held.
next prev parent reply other threads:[~2026-06-29 11:37 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-26 20:36 [PATCH bpf v2 0/4] bpf, sockmap: Fix sockmap leaking UDP socks Michal Luczaj
2026-06-26 20:36 ` [PATCH bpf v2 1/4] bpf, sockmap: Reject unhashed UDP sockets on sockmap update Michal Luczaj
2026-06-26 20:45 ` Kuniyuki Iwashima
2026-06-26 20:58 ` sashiko-bot
2026-06-28 21:59 ` Michal Luczaj
2026-06-29 11:37 ` Jakub Sitnicki [this message]
2026-06-29 21:40 ` Michal Luczaj
2026-07-01 10:04 ` Jakub Sitnicki
2026-07-01 22:58 ` John Fastabend
2026-07-01 23:19 ` Michal Luczaj
2026-06-29 11:38 ` Jakub Sitnicki
2026-07-01 22:59 ` John Fastabend
2026-06-26 20:36 ` [PATCH bpf v2 2/4] selftests/bpf: Ensure UDP sockets are bound Michal Luczaj
2026-06-26 20:47 ` Kuniyuki Iwashima
2026-06-28 21:58 ` Michal Luczaj
2026-06-26 20:36 ` [PATCH bpf v2 3/4] selftests/bpf: Adapt sockmap update error handling Michal Luczaj
2026-06-26 20:43 ` sashiko-bot
2026-06-28 21:58 ` Michal Luczaj
2026-06-26 20:58 ` Kuniyuki Iwashima
2026-06-28 21:59 ` Michal Luczaj
2026-06-26 21:14 ` bot+bpf-ci
2026-06-26 20:36 ` [PATCH bpf v2 4/4] selftests/bpf: Fail unbound UDP on sockmap update Michal Luczaj
2026-06-26 20:41 ` sashiko-bot
2026-06-28 21:58 ` Michal Luczaj
2026-06-26 21:03 ` Kuniyuki Iwashima
2026-07-01 23:19 ` Michal Luczaj
2026-06-27 17:34 ` [PATCH bpf v2 0/4] bpf, sockmap: Fix sockmap leaking UDP socks sun jian
2026-06-28 22:00 ` Michal Luczaj
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