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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH net v5] bpf, net: Fix a potential race in do_sock_getsockopt() Message-ID: References: <20240830082518.23243-1-Tze-nan.Wu@mediatek.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240830082518.23243-1-Tze-nan.Wu@mediatek.com> On 08/30, Tze-nan Wu wrote: > There's a potential race when `cgroup_bpf_enabled(CGROUP_GETSOCKOPT)` is > false during the execution of `BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN`, but > becomes true when `BPF_CGROUP_RUN_PROG_GETSOCKOPT` is called. > This inconsistency can lead to `BPF_CGROUP_RUN_PROG_GETSOCKOPT` receiving > an "-EFAULT" from `__cgroup_bpf_run_filter_getsockopt(max_optlen=0)`. > Scenario shown as below: > > `process A` `process B` > ----------- ------------ > BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN > enable CGROUP_GETSOCKOPT > BPF_CGROUP_RUN_PROG_GETSOCKOPT (-EFAULT) > > To resolve this, remove the `BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN` macro and > directly uses `copy_from_sockptr` to ensure that `max_optlen` is always > set before `BPF_CGROUP_RUN_PROG_GETSOCKOPT` is invoked. > > Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks") > Co-developed-by: Yanghui Li > Signed-off-by: Yanghui Li > Co-developed-by: Cheng-Jui Wang > Signed-off-by: Cheng-Jui Wang > Signed-off-by: Tze-nan Wu Acked-by: Stanislav Fomichev