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[198.162.52.65]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84f5a552859sm172922b3a.42.2026.08.06.17.44.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 17:44:11 -0700 (PDT) From: Ning Ding To: bpf@vger.kernel.org Cc: memxor@gmail.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, shuah@kernel.org, Ning Ding Subject: [PATCH bpf-next 2/2] selftests/bpf: Test RCU iterator state pruning Date: Thu, 6 Aug 2026 17:43:20 -0700 Message-ID: <20260807004320.134069-3-dingning04@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260807004320.134069-1-dingning04@gmail.com> References: <20260807004320.134069-1-dingning04@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a path where RCU protection reaches zero and then starts again. The iterator is untrusted after this gap and must be rejected. Signed-off-by: Ning Ding --- .../selftests/bpf/progs/iters_task_failure.c | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/iters_task_failure.c b/tools/testing/selftests/bpf/progs/iters_task_failure.c index fe3663dedbe14..bac394ae77f44 100644 --- a/tools/testing/selftests/bpf/progs/iters_task_failure.c +++ b/tools/testing/selftests/bpf/progs/iters_task_failure.c @@ -61,6 +61,33 @@ int BPF_PROG(iter_tasks_lock_and_unlock) return 0; } +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") +__failure __msg("expected an RCU CS when using bpf_iter_task_next") +__flag(BPF_F_TEST_STATE_FREQ) +int BPF_PROG(iter_tasks_rcu_state_pruning) +{ + struct bpf_iter_task it; + + bpf_rcu_read_lock(); + bpf_iter_task_new(&it, NULL, BPF_TASK_ITER_ALL_PROCS); + + if (likely(bpf_get_prandom_u32())) { + /* Keep the outer RCU lock active. */ + bpf_rcu_read_lock(); + bpf_rcu_read_unlock(); + } else { + /* Create an unprotected gap. */ + bpf_rcu_read_unlock(); + bpf_rcu_read_lock(); + } + + bpf_iter_task_next(&it); + bpf_iter_task_destroy(&it); + bpf_rcu_read_unlock(); + + return 0; +} + SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") __failure __msg("expected an RCU CS when using bpf_iter_css_next") int BPF_PROG(iter_css_lock_and_unlock) -- 2.43.0