From: Yonghong Song <yhs@meta.com>
To: Kui-Feng Lee <kuifeng@meta.com>,
bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org,
kernel-team@meta.com, song@kernel.org
Cc: Nathan Slingerland <slinger@meta.com>
Subject: Re: [PATCH bpf-next 1/2] bpf: keep a reference to the mm, in case the task is dead.
Date: Fri, 16 Dec 2022 11:09:38 -0800 [thread overview]
Message-ID: <c29f26ac-3b99-4603-295f-ffd80d9223d1@meta.com> (raw)
In-Reply-To: <20221216015912.991616-2-kuifeng@meta.com>
On 12/15/22 5:59 PM, Kui-Feng Lee wrote:
> Fix the system crash that happens when a task iterator travel through
> vma of tasks.
>
> In task iterators, we used to access mm by following the pointer on
> the task_struct; however, the death of a task will clear the pointer,
> even though we still hold the task_struct. That can cause an
> unexpected crash for a null pointer when an iterator is visiting a
> task that dies during the visit. Keeping a reference of mm on the
> iterator ensures we always have a valid pointer to mm.
>
> Co-developed-by: Song Liu <song@kernel.org>
> Signed-off-by: Song Liu <song@kernel.org>
> Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
> Reported-by: Nathan Slingerland <slinger@meta.com>
Acked-by: Yonghong Song <yhs@fb.com>
next prev parent reply other threads:[~2022-12-16 19:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-16 1:59 [PATCH bpf-next 0/2] bpf: fix the crash caused by task iterators over vma Kui-Feng Lee
2022-12-16 1:59 ` [PATCH bpf-next 1/2] bpf: keep a reference to the mm, in case the task is dead Kui-Feng Lee
2022-12-16 19:09 ` Yonghong Song [this message]
2022-12-16 1:59 ` [PATCH bpf-next 2/2] selftests/bpf: create new processes repeatedly in the background Kui-Feng Lee
2022-12-16 20:05 ` Yonghong Song
2022-12-16 21:44 ` Kui-Feng Lee
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