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[198.162.52.65]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84f5a552859sm172922b3a.42.2026.08.06.17.44.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 17:44:09 -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 1/2] bpf: Compare iterator types during state pruning Date: Thu, 6 Aug 2026 17:43:19 -0700 Message-ID: <20260807004320.134069-2-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: quoted-printable Content-Type: text/plain; charset="utf-8" An iterator stack slot can be MEM_RCU or PTR_UNTRUSTED. These states must not be equal, or the verifier can prune an unsafe path. Compare the pointer type for STACK_ITER slots. Fixes: dfab99df147b ("bpf: teach the verifier to enforce css_iter and task_= iter in RCU CS") Signed-off-by: Ning Ding Acked-by: Eduard Zingerman --- kernel/bpf/states.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/states.c b/kernel/bpf/states.c index ea2153cf28d0a..4e6aafad33bd2 100644 --- a/kernel/bpf/states.c +++ b/kernel/bpf/states.c @@ -812,7 +812,8 @@ static bool stacksafe(struct bpf_verifier_env *env, str= uct bpf_func_state *old, * infinite loop check triggering, see * iter_active_depths_differ() */ - if (old_reg->iter.btf !=3D cur_reg->iter.btf || + if (old_reg->type !=3D cur_reg->type || + old_reg->iter.btf !=3D cur_reg->iter.btf || old_reg->iter.btf_id !=3D cur_reg->iter.btf_id || old_reg->iter.state !=3D cur_reg->iter.state || /* ignore {old_reg,cur_reg}->iter.depth, see above */ --=20 2.43.0 From nobody Tue Sep 29 13:55:44 2026 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C5D223D7F4 for ; 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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: quoted-printable Content-Type: text/plain; charset="utf-8" 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; } =20 +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) --=20 2.43.0