From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-242.mta1.migadu.com [95.215.58.242]) (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 B49F3DF6C for ; Thu, 20 Aug 2026 00:06:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.242 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787184407; cv=none; b=K7mK3FBXXZz3+MadXOPP0U9TxI0xYETGE37H5TcTwhyDnNdvZA4KPkNKe1CqIRHSLdwyNuDaZiqhjmwWN6IV/AR+Ps2z8oAw4uK8L2i0dzaAMQmplwOlvg3kf81KomEZ5D+4kFv/0ppnUBvFaSoZI57hvS7KbKcFZq2QlgOvoHk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787184407; c=relaxed/simple; bh=gR5lXPLc9vfaIbqC7fExLn+NcQM0QYa0WDm8PnbxO98=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EaV2w4BxTnyKk1RT+pkGrhkl0ME3jzr+mLZLd7/MzE8rAZ7NeyD1TyUWyANXtz3IVx33sLXtN2HnQdwauglU53tbbxJPvlZaMjEK9uszFmQSonad1BEwmLqIZf55tMvgKzym1fDEC/rmd6GkcQ1ervnfnra/ZfeMNdbGwIzyaIQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=SiiNO0k/; arc=none smtp.client-ip=95.215.58.242 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="SiiNO0k/" X-Envelope-To: bpf@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=gR5lXPLc9vfaIbqC7fExLn+NcQM0QYa0WDm8PnbxO98=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787184402; v=1; x=1787789202; b=SiiNO0k/26RO7uc5/e4aU3ij4v5hjmY41Hi5fUmRiSAygRKdfBJCoCeEMSBpqBKkSlihaVVM TCkoOdrRvgqxoFsCGLuwthw5fw7PUmW6SXKxFlJkMFVvV4Vn3cZxDZ1E64bz7wQJaB9L2l+ueqC sm3eC8yRriWwLR/VWAyxdfdU= X-Envelope-To: bpf@vger.kernel.org Received: from isolodrai-fedora-MJ0FVMD1.thefacebook.com (2620:10d:c090:500::5:942a) by mta11.migadu.com with ESMTPS id 05d2717b1b930804; Thu, 20 Aug 2026 00:06:42 +0000 X-Mizu-Trace-ID: 05d2717b1b930804 X-Migadu-Flow: FLOW_OUT From: Ihor Solodrai To: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Kumar Kartikeya Dwivedi , Quentin Monnet Cc: bpf@vger.kernel.org Subject: [PATCH bpf-next v1 1/4] selftests/bpf: NUL-terminate bpftool command output Date: Wed, 19 Aug 2026 17:06:24 -0700 Message-ID: <20260820000627.3826188-2-ihor.solodrai@linux.dev> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820000627.3826188-1-ihor.solodrai@linux.dev> References: <20260820000627.3826188-1-ihor.solodrai@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit run_command() writes a bpftool command's output into a caller-supplied buffer, and every caller treats that buffer as a C string. 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. Read one byte less and terminate in the helper. Fixes: f21fae577446 ("selftests/bpf: Add a few helpers for bpftool testing") Signed-off-by: Ihor Solodrai --- tools/testing/selftests/bpf/bpftool_helpers.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/bpftool_helpers.c b/tools/testing/selftests/bpf/bpftool_helpers.c index 0a2a4f0a2794..c49fdd90eb03 100644 --- a/tools/testing/selftests/bpf/bpftool_helpers.c +++ b/tools/testing/selftests/bpf/bpftool_helpers.c @@ -53,6 +53,7 @@ static int run_command(char *args, char *output_buf, size_t output_max_len) static char bpftool_path[PATH_MAX] = {}; bool suppress_output = !(output_buf && output_max_len); char command[BPFTOOL_FULL_CMD_MAX_LEN]; + size_t n; FILE *f; int ret; @@ -68,8 +69,10 @@ static int run_command(char *args, char *output_buf, size_t output_max_len) if (!f) return 1; - if (!suppress_output) - fread(output_buf, 1, output_max_len, f); + if (!suppress_output) { + n = fread(output_buf, 1, output_max_len - 1, f); + output_buf[n] = '\0'; + } ret = pclose(f); return ret; -- 2.55.0