From b5a36b1e1b138285ea0df34bf96c759e1e30fafd Mon Sep 17 00:00:00 2001 From: Lorenz Bauer Date: Mon, 3 Dec 2018 11:31:23 +0000 Subject: bpf: respect size hint to BPF_PROG_TEST_RUN if present Use data_size_out as a size hint when copying test output to user space. ENOSPC is returned if the output buffer is too small. Callers which so far did not set data_size_out are not affected. Signed-off-by: Lorenz Bauer Signed-off-by: Alexei Starovoitov --- net/bpf/test_run.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'net/bpf/test_run.c') diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index c89c22c49015..7663e6a57280 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -74,8 +74,18 @@ static int bpf_test_finish(const union bpf_attr *kattr, { void __user *data_out = u64_to_user_ptr(kattr->test.data_out); int err = -EFAULT; + u32 copy_size = size; + + /* Clamp copy if the user has provided a size hint, but copy the full + * buffer if not to retain old behaviour. + */ + if (kattr->test.data_size_out && + copy_size > kattr->test.data_size_out) { + copy_size = kattr->test.data_size_out; + err = -ENOSPC; + } - if (data_out && copy_to_user(data_out, data, size)) + if (data_out && copy_to_user(data_out, data, copy_size)) goto out; if (copy_to_user(&uattr->test.data_size_out, &size, sizeof(size))) goto out; @@ -83,7 +93,8 @@ static int bpf_test_finish(const union bpf_attr *kattr, goto out; if (copy_to_user(&uattr->test.duration, &duration, sizeof(duration))) goto out; - err = 0; + if (err != -ENOSPC) + err = 0; out: return err; } -- cgit v1.2.3-59-g8ed1b