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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49cf7740d44sm34096505e9.15.2026.09.03.14.48.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Sep 2026 14:48:08 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Emil Tsalapatis , Nicholas Carlini , kkd@meta.com, kernel-team@meta.com Subject: [PATCH bpf v1 6/8] selftests/bpf: Check faultable stack helper contexts Date: Thu, 3 Sep 2026 23:47:52 +0200 Message-ID: <20260903214758.2727663-7-memxor@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260903214758.2727663-1-memxor@gmail.com> References: <20260903214758.2727663-1-memxor@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2425; i=memxor@gmail.com; h=from:subject; bh=qJdfWxdDnKj13XrhJaZHd4m24v164U7oUc/dypgIVfw=; b=owGbwMvMwCXmrmtenRyi38x4Wi2JIWvma9a28KuGVbFVj4IPN/k0c6+b7N9hUD313KsVV6KUc mwiCqw6SlkYxLgYZMUUWUr+72MyPlH5O9B2GTfMHFYmkCEMXJwCMBHjGwz/tOZWb0n8vcFs7hph lecbsnqrL2+8+fGq/Svfaa8bd2j+42b4H//U/3aQfWpLNvd5E87NJ61bzgey8e1qlcoItmDeNuU WNwA= X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=B34BD741DE8494B76E2F717880EF20021D46C59B Content-Transfer-Encoding: 8bit Add verifier coverage for the sleepable bpf_get_stack() and bpf_get_task_stack() implementations. Call each helper while preemption is disabled and require the verifier to reject it as sleepable. Both programs load when the prototypes lack might_sleep, so the expected-failure tests fail. Keep success controls outside the non-preemptible region to ensure ordinary calls from sleepable uprobes remain valid. Signed-off-by: Kumar Kartikeya Dwivedi --- .../selftests/bpf/progs/preempt_lock.c | 52 +++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/preempt_lock.c b/tools/testing/selftests/bpf/progs/preempt_lock.c index 6d5fce7e6ffc..81c459435680 100644 --- a/tools/testing/selftests/bpf/progs/preempt_lock.c +++ b/tools/testing/selftests/bpf/progs/preempt_lock.c @@ -115,6 +115,58 @@ int preempt_sleepable_helper(void *ctx) return 0; } +SEC("?uprobe.s") +__failure __msg("sleepable helper bpf_get_stack#") +int preempt_sleepable_get_stack(struct pt_regs *ctx) +{ + struct bpf_stack_build_id stack; + + bpf_preempt_disable(); + bpf_get_stack(ctx, &stack, sizeof(stack), + BPF_F_USER_STACK | BPF_F_USER_BUILD_ID); + bpf_preempt_enable(); + return 0; +} + +SEC("?uprobe.s") +__failure __msg("sleepable helper bpf_get_task_stack#") +int preempt_sleepable_get_task_stack(void *ctx) +{ + struct bpf_stack_build_id stack; + struct task_struct *task; + + task = bpf_get_current_task_btf(); + bpf_preempt_disable(); + bpf_get_task_stack(task, &stack, sizeof(stack), + BPF_F_USER_STACK | BPF_F_USER_BUILD_ID); + bpf_preempt_enable(); + return 0; +} + +SEC("?uprobe.s") +__success +int sleepable_get_stack(struct pt_regs *ctx) +{ + struct bpf_stack_build_id stack; + + bpf_get_stack(ctx, &stack, sizeof(stack), + BPF_F_USER_STACK | BPF_F_USER_BUILD_ID); + return 0; +} + +SEC("?uprobe.s") +__success +int sleepable_get_task_stack(void *ctx) +{ + struct bpf_stack_build_id stack; + struct task_struct *task; + + task = bpf_get_current_task_btf(); + bpf_get_task_stack(task, &stack, sizeof(stack), + BPF_F_USER_STACK | BPF_F_USER_BUILD_ID); + return 0; +} + SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") __failure __msg("kernel func bpf_copy_from_user_str is sleepable within non-preemptible region") int preempt_sleepable_kfunc(void *ctx) -- 2.53.0