From: Jakub Sitnicki <jakub@cloudflare•com>
To: Alexei Starovoitov <alexei.starovoitov@gmail•com>,
Edward Adam Davis <eadavis@qq•com>,
John Fastabend <john.fastabend@gmail•com>
Cc: syzbot+c4f4d25859c2e5859988@syzkaller•appspotmail.com,
42.hyeyoo@gmail•com, andrii@kernel•org, ast@kernel•org,
bpf@vger•kernel.org, daniel@iogearbox•net, davem@davemloft•net,
edumazet@google•com, kafai@fb•com, kpsingh@kernel•org,
kuba@kernel•org, linux-kernel@vger•kernel.org,
namhyung@kernel•org, netdev@vger•kernel.org, pabeni@redhat•com,
peterz@infradead•org, songliubraving@fb•com,
syzkaller-bugs@googlegroups•com, yhs@fb•com
Subject: Re: [PATCH] bpf, sockmap: fix deadlock in rcu_report_exp_cpu_mult
Date: Mon, 25 Mar 2024 14:49:19 +0100 [thread overview]
Message-ID: <87ttkuber7.fsf@cloudflare.com> (raw)
In-Reply-To: <87y1a6biie.fsf@cloudflare.com>
On Mon, Mar 25, 2024 at 01:23 PM +01, Jakub Sitnicki wrote:
[...]
> But we also need to cover sock_map_unref->sock_sock_map_del_link called
> from sock_hash_delete_elem. It also grabs a spin lock.
On second look, no need to disable interrupts in
sock_map_unref->sock_sock_map_del_link. Call is enclosed in the critical
section in sock_hash_delete_elem that has been updated.
I have a question, though, why are we patching sock_hash_free? It
doesn't get called unless there are no more existing users of the BPF
map. So nothing can mutate it from interrupt context.
[...]
next prev parent reply other threads:[~2024-03-25 13:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-18 10:07 [syzbot] [bpf?] [net?] possible deadlock in rcu_report_exp_cpu_mult syzbot
2024-03-23 5:42 ` [PATCH] bpf, sockmap: fix " Edward Adam Davis
2024-03-23 7:08 ` Alexei Starovoitov
2024-03-25 12:23 ` Jakub Sitnicki
2024-03-25 13:49 ` Jakub Sitnicki [this message]
2024-03-29 5:29 ` John Fastabend
2024-03-26 22:15 ` Jakub Sitnicki
2024-03-29 15:52 ` Shung-Hsi Yu
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