From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC4F21E284A; Fri, 4 Oct 2024 18:18:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728065918; cv=none; b=aGi5vUjpQwjgrYQn7SC6jImE+O9levynBb79S9jIo3kmo6hRPhRW2ZfF+06kRtY3rgIL9sbWJ60tigvmrsZpGIP2AQqX5hLjEC/gsb3enya9oofY28m5qSltzkKzpm041Cc6zxXG51jZRrbkjlGzQrAHvtTwGU/jgcOidPf5rY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728065918; c=relaxed/simple; bh=2my7iZVJrU4CA6w35Blro+3kSQHI5GlKSS8Rl/NZ5/8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A0N6GKOX4x3EP9cqKHvVc42Hy27xV+qTX9c9M5lT3uIUC0xDHAhjgBa9xivKRXQppNfK60Va4Q7zPzpIG+UknT0eq7yiF6dMXmMUSl5UWew0kicGzKwuii2bl1BhP7xt/UHdhowU+17uBV3tOssbjuXWeif0v7cSz3eFywk+l24= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DhpcrzUH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DhpcrzUH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 475D8C4CECD; Fri, 4 Oct 2024 18:18:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728065918; bh=2my7iZVJrU4CA6w35Blro+3kSQHI5GlKSS8Rl/NZ5/8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DhpcrzUHnbBOoS87hlywje7n9dTNz0ZNgDIoJ6n6G1qhetCN/Gj7gFbAZNzHpgiTd LK+Hg/vxo4OoKBy9Gwqd5b1EZGRTQpU5yB7aQyUyCVDM+HOU4sHfaKXJuy6qpK39T5 j5ccNAnC3TvWlQpifnBI4dda1TASOdLQW1Wlq0md/R+ITdwF0FIWEQ6YFfqyRo/w6E jkftCbYTEn7Q5iVBDHT9lZNm/bWf7MxOZdp2JrkehJXg7L6UDKppte+CD7MZ3hy/7U Hp0BV42atxfiy37RfPN1kvNXLqtzibfEgitMcr8CBrfY0b0qL87Wm4tTw5zR3gtsRM wLHLTs1yIDu1g== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Andrii Nakryiko , Quentin Monnet , Sasha Levin , ast@kernel.org, daniel@iogearbox.net, bpf@vger.kernel.org Subject: [PATCH AUTOSEL 6.11 05/76] bpftool: Fix undefined behavior in qsort(NULL, 0, ...) Date: Fri, 4 Oct 2024 14:16:22 -0400 Message-ID: <20241004181828.3669209-5-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241004181828.3669209-1-sashal@kernel.org> References: <20241004181828.3669209-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.11.2 Content-Transfer-Encoding: 8bit From: Kuan-Wei Chiu [ Upstream commit f04e2ad394e2755d0bb2d858ecb5598718bf00d5 ] When netfilter has no entry to display, qsort is called with qsort(NULL, 0, ...). This results in undefined behavior, as UBSan reports: net.c:827:2: runtime error: null pointer passed as argument 1, which is declared to never be null Although the C standard does not explicitly state whether calling qsort with a NULL pointer when the size is 0 constitutes undefined behavior, Section 7.1.4 of the C standard (Use of library functions) mentions: "Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointer to non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after promotion) not expected by a function with variable number of arguments, the behavior is undefined." To avoid this, add an early return when nf_link_info is NULL to prevent calling qsort with a NULL pointer. Signed-off-by: Kuan-Wei Chiu Signed-off-by: Andrii Nakryiko Reviewed-by: Quentin Monnet Link: https://lore.kernel.org/bpf/20240910150207.3179306-1-visitorckw@gmail.com Signed-off-by: Sasha Levin --- tools/bpf/bpftool/net.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c index 968714b4c3d45..0ad684e810f34 100644 --- a/tools/bpf/bpftool/net.c +++ b/tools/bpf/bpftool/net.c @@ -824,6 +824,9 @@ static void show_link_netfilter(void) nf_link_count++; } + if (!nf_link_info) + return; + qsort(nf_link_info, nf_link_count, sizeof(*nf_link_info), netfilter_link_compar); for (id = 0; id < nf_link_count; id++) { -- 2.43.0