From: Hou Tao <houtao@huaweicloud.com>
To: Pu Lehui <pulehui@huaweicloud.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Xu Kuohai <xukuohai@huawei.com>,
Pu Lehui <pulehui@huawei.com>
Subject: Re: [PATCH bpf] bpf: cpumap: Fix memory leak in cpu_map_update_elem
Date: Wed, 12 Jul 2023 10:12:02 +0800 [thread overview]
Message-ID: <e065f385-3baf-eacb-7ca5-6ade14491eee@huaweicloud.com> (raw)
In-Reply-To: <20230711115848.2701559-1-pulehui@huaweicloud.com>
On 7/11/2023 7:58 PM, Pu Lehui wrote:
> From: Pu Lehui <pulehui@huawei.com>
>
> Syzkaller reported a memory leak as follows:
>
> BUG: memory leak
> unreferenced object 0xff110001198ef748 (size 192):
> comm "syz-executor.3", pid 17672, jiffies 4298118891 (age 9.906s)
> hex dump (first 32 bytes):
> 00 00 00 00 4a 19 00 00 80 ad e3 e4 fe ff c0 00 ....J...........
> 00 b2 d3 0c 01 00 11 ff 28 f5 8e 19 01 00 11 ff ........(.......
> backtrace:
> [<ffffffffadd28087>] __cpu_map_entry_alloc+0xf7/0xb00
> [<ffffffffadd28d8e>] cpu_map_update_elem+0x2fe/0x3d0
> [<ffffffffadc6d0fd>] bpf_map_update_value.isra.0+0x2bd/0x520
> [<ffffffffadc7349b>] map_update_elem+0x4cb/0x720
> [<ffffffffadc7d983>] __se_sys_bpf+0x8c3/0xb90
> [<ffffffffb029cc80>] do_syscall_64+0x30/0x40
> [<ffffffffb0400099>] entry_SYSCALL_64_after_hwframe+0x61/0xc6
>
> BUG: memory leak
> unreferenced object 0xff110001198ef528 (size 192):
> comm "syz-executor.3", pid 17672, jiffies 4298118891 (age 9.906s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<ffffffffadd281f0>] __cpu_map_entry_alloc+0x260/0xb00
> [<ffffffffadd28d8e>] cpu_map_update_elem+0x2fe/0x3d0
> [<ffffffffadc6d0fd>] bpf_map_update_value.isra.0+0x2bd/0x520
> [<ffffffffadc7349b>] map_update_elem+0x4cb/0x720
> [<ffffffffadc7d983>] __se_sys_bpf+0x8c3/0xb90
> [<ffffffffb029cc80>] do_syscall_64+0x30/0x40
> [<ffffffffb0400099>] entry_SYSCALL_64_after_hwframe+0x61/0xc6
>
> BUG: memory leak
> unreferenced object 0xff1100010fd93d68 (size 8):
> comm "syz-executor.3", pid 17672, jiffies 4298118891 (age 9.906s)
> hex dump (first 8 bytes):
> 00 00 00 00 00 00 00 00 ........
> backtrace:
> [<ffffffffade5db3e>] kvmalloc_node+0x11e/0x170
> [<ffffffffadd28280>] __cpu_map_entry_alloc+0x2f0/0xb00
> [<ffffffffadd28d8e>] cpu_map_update_elem+0x2fe/0x3d0
> [<ffffffffadc6d0fd>] bpf_map_update_value.isra.0+0x2bd/0x520
> [<ffffffffadc7349b>] map_update_elem+0x4cb/0x720
> [<ffffffffadc7d983>] __se_sys_bpf+0x8c3/0xb90
> [<ffffffffb029cc80>] do_syscall_64+0x30/0x40
> [<ffffffffb0400099>] entry_SYSCALL_64_after_hwframe+0x61/0xc6
>
> In the cpu_map_update_elem flow, when kthread_stop is called before
> calling the threadfn of rcpu->kthread, since the KTHREAD_SHOULD_STOP bit
> of kthread has been set by kthread_stop, the threadfn of rcpu->kthread
> will never be executed, and rcpu->refcnt will never be 0, which will
> lead to the allocated rcpu, rcpu->queue and rcpu->queue->queue cannot be
> released.
>
> Calling kthread_stop before executing kthread's threadfn will return
> -EINTR. We can complete the release of memory resources in this state.
>
> Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
> Signed-off-by: Pu Lehui <pulehui@huawei.com>
Acked-by: Hou Tao <houtao1@huawei.com>
next prev parent reply other threads:[~2023-07-12 2:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-11 11:58 Pu Lehui
2023-07-11 16:06 ` Jesper Dangaard Brouer
2023-07-12 2:12 ` Hou Tao [this message]
2023-07-12 3:04 ` Alexei Starovoitov
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