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Message-ID: <a6f8b4a4-2c37-740b-af87-c61af51eaab5@huaweicloud.com>
Date:   Mon, 21 Nov 2022 19:30:09 +0800
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Subject: Re: [PATCH bpf 1/2] bpf: Do not copy spin lock field from user in
 bpf_selem_alloc
Content-Language: en-US
From:   Xu Kuohai <xukuohai@huaweicloud.com>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
        Kumar Kartikeya Dwivedi <memxor@gmail.com>,
        Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>
References: <20221114134720.1057939-1-xukuohai@huawei.com>
 <20221114134720.1057939-2-xukuohai@huawei.com>
 <CAADnVQLEzrqjuF+qYh2kJz0Q=9G8PySJ6ZwXD2EGoZsBUdwsog@mail.gmail.com>
 <fd1e6d2d-f7a2-21d2-f0ff-3e3d8b2ba9eb@huawei.com>
In-Reply-To: <fd1e6d2d-f7a2-21d2-f0ff-3e3d8b2ba9eb@huawei.com>
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On 11/16/2022 4:07 PM, Xu Kuohai wrote:
> On 11/16/2022 1:27 PM, Alexei Starovoitov wrote:
>> On Mon, Nov 14, 2022 at 5:31 AM Xu Kuohai <xukuohai@huawei.com> wrote:
>>>
>>> bpf_selem_alloc function is used by inode_storage, sk_storage and
>>> task_storage maps to set map value, for these map types, there may
>>> be a spin lock in the map value, so if we use memcpy to copy the whole
>>> map value from user, the spin lock field may be initialized incorrectly.
>>>
>>> Since the spin lock field is zeroed by kzalloc, call copy_map_value
>>> instead of memcpy to skip copying the spin lock field to fix it.
>>>
>>> Fixes: 6ac99e8f23d4 ("bpf: Introduce bpf sk local storage")
>>
>> The tag is wrong. When local storage was introduced it was not
>> possible to use spin_locks there.
>> Pls resubmit.
>> .
> 
> No, spin_lock was introduced by d83525ca62cf ("bpf: introduce bpf_spin_lock"),
> before 6ac99e8f23d4 ("bpf: Introduce bpf sk local storage").
> 
> To confirm this, I built a kernel image on comit 6ac99e8f23d4 ("bpf: Introduce bpf sk local storage")
> and run test case posted in patch 2, a softlockup was triggered. Then I picked
> this patch and tried again, nothing failed.

Hello, am I right? Or could you please give the correct fix-tag? Thanks.