From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-131.mta0.migadu.com [91.218.175.131]) (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 085AD3955F7 for ; Fri, 28 Aug 2026 21:52:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787953954; cv=none; b=MjQI9KzQgimBHCP8WO5xwOt8a7tUETit+QvOhP8gWN1zfzNhoHUi2wcjnTLgcrkkV0lCt836Su6i3XTKIWSyIYWd9KBPbWVjA0vE+tngdWaC3Z7/BSfFz0xeqr2bY6uq/WcHhCyfEcQ4b3Ok8yliO4CO/10Xss3cv4mHSQFPxG0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787953954; c=relaxed/simple; bh=XhMNdur0mR9N7zXM4n4hm/ZvNoYiLMHCBkxWTgCP+nQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ozxvy5KqMjdiSj07+07XflpCVZ6dnEZyGFmyVVkInUsipM30eKOCWbJubYQKMJ0Sx0Ceib4ud2vFi5ZQfAvRvS0u6hEXeuWPV0Zd5W3By71vJpHznGhK37gJYoQRHpMv02+K5iOB4Iknojvk9znjArNfD/XHH8Ao+xFTUbDbTEw= 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=EqRTeIoF; arc=none smtp.client-ip=91.218.175.131 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="EqRTeIoF" X-Envelope-To: bpf@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=XhMNdur0mR9N7zXM4n4hm/ZvNoYiLMHCBkxWTgCP+nQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787953951; v=1; x=1788558751; b=EqRTeIoF/VZ9veszvQ6VDdGjgWAiWsi4qXuVzjawSZg4LlSse+L5w+oCDBwdWJdaoCFp1TC5 +GgqEiCqdtwWWE1qAwd4P7f9ZBZzc9uAbLXfLxPUkhPV+T6OAq9FQF3SRSnAhl4oBfbqi0WCwbr RLT45gB1+o2huQb0z0xFO0h0= X-Envelope-To: bpf@vger.kernel.org Received: by mta11.migadu.com with ESMTPS id e83447fb8f14049f; Fri, 28 Aug 2026 21:52:31 +0000 X-Mizu-Trace-ID: e83447fb8f14049f 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 v2 4/6] selftests/bpf: NUL-terminate bpftool command output Date: Fri, 28 Aug 2026 14:52:05 -0700 Message-ID: <20260828215207.3105313-5-ihor.solodrai@linux.dev> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260828215207.3105313-1-ihor.solodrai@linux.dev> References: <20260828215207.3105313-1-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") Acked-by: Eduard Zingerman 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