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[116.14.95.136]) by smtp.gmail.com with ESMTPSA id z1-20020a170902708100b001bdeb6bdfbasm2775579plk.241.2023.09.17.07.29.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 17 Sep 2023 07:29:50 -0700 (PDT) Message-ID: <3a354608-6685-ee51-6317-9bf127cfd7b8@gmail.com> Date: Sun, 17 Sep 2023 22:29:44 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH bpf] bpf: Fix tr dereferencing Content-Language: en-US To: Alexei Starovoitov , Hengqi Chen Cc: bpf , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= , Stanislav Fomichev , kbuild test robot , Dan Carpenter , "Fijalkowski, Maciej" , kernel-patches-bot@fb.com References: <20230914145126.40202-1-hffilwlqm@gmail.com> <8148921c-cc06-bad7-787f-d190cba0bce1@gmail.com> From: Leon Hwang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-3.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,HK_RANDOM_ENVFROM, HK_RANDOM_FROM,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 2023/9/16 01:38, Alexei Starovoitov wrote: > On Thu, Sep 14, 2023 at 7:54 PM Hengqi Chen wrote: >> >> On Fri, Sep 15, 2023 at 10:18 AM Leon Hwang wrote: >>> >>> >>> >>> On 15/9/23 10:13, Hengqi Chen wrote: >>>> On Thu, Sep 14, 2023 at 10:51 PM Leon Hwang wrote: >>>>> >>>>> Fix 'tr' dereferencing bug when CONFIG_BPF_JIT is turned off. >>>>> >>>>> Like 'bpf_trampoline_get_progs()', return 'ERR_PTR()' and then check by >>>>> 'IS_ERR()'. As a result, when CONFIG_BPF_JIT is turned off, it's able to >>>>> handle the case that 'bpf_trampoline_get()' returns >>>>> 'ERR_PTR(-EOPNOTSUPP)'. >>>>> >>>>> Fixes: 4a1e7c0c63e0 ("bpf: Support attaching freplace programs to multiple attach points") >>>>> Fixes: f7b12b6fea00 ("bpf: verifier: refactor check_attach_btf_id()") >>>>> Fixes: 69fd337a975c ("bpf: per-cgroup lsm flavor") >>>>> Reported-by: kernel test robot >>>>> Reported-by: Dan Carpenter >>>>> Closes: https://lore.kernel.org/r/202309131936.5Nc8eUD0-lkp@intel.com/ >>>>> Signed-off-by: Leon Hwang >>>>> --- >>>>> kernel/bpf/syscall.c | 4 ++-- >>>>> kernel/bpf/trampoline.c | 6 +++--- >>>>> kernel/bpf/verifier.c | 4 ++-- >>>>> 3 files changed, 7 insertions(+), 7 deletions(-) >>>>> >>>>> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c >>>>> index 6a692f3bea150..5748d01c99854 100644 >>>>> --- a/kernel/bpf/syscall.c >>>>> +++ b/kernel/bpf/syscall.c >>>>> @@ -3211,8 +3211,8 @@ static int bpf_tracing_prog_attach(struct bpf_prog *prog, >>>>> } >>>>> >>>>> tr = bpf_trampoline_get(key, &tgt_info); >>>>> - if (!tr) { >>>>> - err = -ENOMEM; >>>>> + if (IS_ERR(tr)) { >>>>> + err = PTR_ERR(tr); >>>>> goto out_unlock; >>>> >>>> IS_ERR does not check the null case, so this should be IS_ERR_OR_NULL instead. >>> >>> Actually, bpf_trampoline_get() would not return NULL. It returns ERR_PTR(-ENOMEM) >>> or a valid ptr. >>> >> >> OK, I missed the change in bpf_trampoline_get(). Anyway, >> >> Reviewed-by: Hengqi Chen > > That's too much churn to address !JIT config. > Just make it return NULL in that case, > instead of hacking things all over the place. OK, I'll do it in v2 patch. Thanks, Leon