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[23.83.224.125]) by smtp.gmail.com with ESMTPSA id x4sm6908651pfn.134.2021.03.12.22.03.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Mar 2021 22:03:09 -0800 (PST) From: Jackie Liu X-Google-Original-From: Jackie Liu To: jolsa@redhat.com, linux-kernel@vger.kernel.org Cc: Jackie Liu , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim Subject: [PATCH v3] perf tools: perf_event_paranoid and kptr_restrict may crash on 'perf top' Date: Sat, 13 Mar 2021 14:02:46 +0800 Message-Id: <20210313060246.37116-1-liuyun01@kylinos.cn> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After install the libelf-dev package and compiling perf, kptr_restrict=2 and perf_event_paranoid=3 will cause perf top to crash, because the value of /proc/kallsyms cannot be obtained, which leads to info->jited_ksyms == NULL. In order to solve this problem, Add a judgment before use. V2->V3: free info_linear memory and move code above, don't do those extra btf checks. Suggested-by: Jiri Olsa Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Mark Rutland Cc: Alexander Shishkin Cc: Namhyung Kim Signed-off-by: Jackie Liu --- tools/perf/util/bpf-event.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c index 57d58c81a5f8..3c03c782bac6 100644 --- a/tools/perf/util/bpf-event.c +++ b/tools/perf/util/bpf-event.c @@ -201,12 +201,18 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session, } info = &info_linear->info; + if (!info->jited_ksyms) { + free(info_linear); + return -1; + } /* number of ksyms, func_lengths, and tags should match */ sub_prog_cnt = info->nr_jited_ksyms; if (sub_prog_cnt != info->nr_prog_tags || - sub_prog_cnt != info->nr_jited_func_lens) + sub_prog_cnt != info->nr_jited_func_lens) { + free(info_linear); return -1; + } /* check BTF func info support */ if (info->btf_id && info->nr_func_info && info->func_info_rec_size) { -- 2.25.1