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Thu, 04 Jun 2026 15:09:09 -0700 (PDT) Received: from localhost ([2a03:2880:ff:6::]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c16629c08bsm70177595ad.61.2026.06.04.15.09.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Jun 2026 15:09:08 -0700 (PDT) From: Amery Hung To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, memxor@gmail.com, martin.lau@kernel.org, mykyta.yatsenko5@gmail.com, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v1 3/3] selftests/bpf: Use bpf_dynptr_slice() to read file dynptr in leak test Date: Thu, 4 Jun 2026 15:09:04 -0700 Message-ID: <20260604220904.1032145-4-ameryhung@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260604220904.1032145-1-ameryhung@gmail.com> References: <20260604220904.1032145-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit use_file_dynptr_slice_after_put_file() reads the dynptr via bpf_dynptr_data(), which always returns NULL for a read-only file dynptr, making the example confusing. Switch to bpf_dynptr_slice(), the correct read API for file dynptrs, and read (rather than write) the slice since it is read-only. The test still fails as expected. Signed-off-by: Amery Hung --- tools/testing/selftests/bpf/progs/file_reader_fail.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/file_reader_fail.c b/tools/testing/selftests/bpf/progs/file_reader_fail.c index d5fae5e4cf9a..3bb9e2612f8f 100644 --- a/tools/testing/selftests/bpf/progs/file_reader_fail.c +++ b/tools/testing/selftests/bpf/progs/file_reader_fail.c @@ -87,7 +87,8 @@ int use_file_dynptr_slice_after_put_file(void *ctx) struct task_struct *task = bpf_get_current_task_btf(); struct file *file = bpf_get_task_exe_file(task); struct bpf_dynptr dynptr; - char *data; + char buf[1]; + const char *data; if (!file) return 0; @@ -95,15 +96,14 @@ int use_file_dynptr_slice_after_put_file(void *ctx) if (bpf_dynptr_from_file(file, 0, &dynptr)) goto out; - data = bpf_dynptr_data(&dynptr, 0, 1); + data = bpf_dynptr_slice(&dynptr, 0, buf, sizeof(buf)); if (!data) goto out; /* this should fail - file dynptr should be discarded first to prevent resource leak */ bpf_put_file(file); - *data = 'x'; - return 0; + return data[0]; out: bpf_dynptr_file_discard(&dynptr); -- 2.53.0-Meta