From: Jiri Olsa <olsajiri@gmail.com>
To: Hou Tao <houtao@huaweicloud.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
stable@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>
Subject: Re: [PATCHv2 bpf 2/2] bpf: Disable preemption in bpf_event_output
Date: Fri, 21 Jul 2023 14:45:10 +0200 [thread overview]
Message-ID: <ZLp91s9kuOp7kEEA@krava> (raw)
In-Reply-To: <0b963b18-4933-3b70-3dc6-6c7150bcf7bb@huaweicloud.com>
On Fri, Jul 21, 2023 at 08:16:14PM +0800, Hou Tao wrote:
>
>
> On 7/20/2023 4:57 PM, Jiri Olsa wrote:
> > We received report [1] of kernel crash, which is caused by
> > using nesting protection without disabled preemption.
> >
> > The bpf_event_output can be called by programs executed by
> > bpf_prog_run_array_cg function that disabled migration but
> > keeps preemption enabled.
> >
> > This can cause task to be preempted by another one inside the
> > nesting protection and lead eventually to two tasks using same
> > perf_sample_data buffer and cause crashes like:
> >
> > BUG: kernel NULL pointer dereference, address: 0000000000000001
> > #PF: supervisor instruction fetch in kernel mode
> > #PF: error_code(0x0010) - not-present page
> > ...
> > ? perf_output_sample+0x12a/0x9a0
> > ? finish_task_switch.isra.0+0x81/0x280
> > ? perf_event_output+0x66/0xa0
> > ? bpf_event_output+0x13a/0x190
> > ? bpf_event_output_data+0x22/0x40
> > ? bpf_prog_dfc84bbde731b257_cil_sock4_connect+0x40a/0xacb
> > ? xa_load+0x87/0xe0
> > ? __cgroup_bpf_run_filter_sock_addr+0xc1/0x1a0
> > ? release_sock+0x3e/0x90
> > ? sk_setsockopt+0x1a1/0x12f0
> > ? udp_pre_connect+0x36/0x50
> > ? inet_dgram_connect+0x93/0xa0
> > ? __sys_connect+0xb4/0xe0
> > ? udp_setsockopt+0x27/0x40
> > ? __pfx_udp_push_pending_frames+0x10/0x10
> > ? __sys_setsockopt+0xdf/0x1a0
> > ? __x64_sys_connect+0xf/0x20
> > ? do_syscall_64+0x3a/0x90
> > ? entry_SYSCALL_64_after_hwframe+0x72/0xdc
> >
> > Fixing this by disabling preemption in bpf_event_output.
> >
> > [1] https://github.com/cilium/cilium/issues/26756
> > Cc: stable@vger.kernel.org
> > Reported-by: Oleg "livelace" Popov <o.popov@livelace.ru>
> > Fixes: 2a916f2f546c bpf: Use migrate_disable/enable in array macros and cgroup/lirc code.
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>
> Acked-by: Hou Tao <houtao1@huawei.com>
>
> With one nit above. The format of the Fixes tags should be 2a916f2f546c
> ("bpf: Use migrate_disable/enable in array macros and cgroup/lirc code.")
>
right, sorry about that.. should I resend?
thanks,
jirka
next prev parent reply other threads:[~2023-07-21 12:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-20 8:57 [PATCHv2 bpf 0/2] bpf: Disable preemption in perf_event_output helpers code Jiri Olsa
2023-07-20 8:57 ` [PATCHv2 bpf 1/2] bpf: Disable preemption in bpf_perf_event_output Jiri Olsa
2023-07-21 11:40 ` Hou Tao
2023-07-20 8:57 ` [PATCHv2 bpf 2/2] bpf: Disable preemption in bpf_event_output Jiri Olsa
2023-07-21 12:16 ` Hou Tao
2023-07-21 12:45 ` Jiri Olsa [this message]
2023-07-21 13:45 ` Hou Tao
2023-07-24 18:01 ` Alexei Starovoitov
2023-07-21 12:12 ` [PATCHv2 bpf 0/2] bpf: Disable preemption in perf_event_output helpers code Hou Tao
2023-07-21 12:44 ` Jiri Olsa
2023-07-21 13:42 ` Hou Tao
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