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([2620:10d:c090:500::6:c5ba]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1416ad3d708sm16233330c88.1.2026.08.20.11.43.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2026 11:43:36 -0700 (PDT) Message-ID: Subject: Re: [PATCH bpf-next v1 1/4] selftests/bpf: NUL-terminate bpftool command output From: Eduard Zingerman To: Ihor Solodrai , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Kumar Kartikeya Dwivedi , Quentin Monnet Cc: bpf@vger.kernel.org Date: Thu, 20 Aug 2026 11:43:34 -0700 In-Reply-To: <20260820000627.3826188-2-ihor.solodrai@linux.dev> References: <20260820000627.3826188-1-ihor.solodrai@linux.dev> <20260820000627.3826188-2-ihor.solodrai@linux.dev> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-1.fc44) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-08-19 at 17:06 -0700, Ihor Solodrai wrote: > run_command() writes a bpftool command's output into a caller-supplied > buffer, and every caller treats that buffer as a C string. >=20 > However fread() reports a byte count and doesn't terminate the > string. The helper does not terminate either, so callers have to zero > the buffer first. prog_tests/bpftool_metadata.c does not, for example. >=20 > Read one byte less and terminate in the helper. >=20 > Fixes: f21fae577446 ("selftests/bpf: Add a few helpers for bpftool testin= g") > Signed-off-by: Ihor Solodrai > --- Acked-by: Eduard Zingerman ...