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 2CA531DED4E; Tue, 8 Oct 2024 13:19:15 +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=1728393555; cv=none; b=pm3pBGUyL2QmD7zXedjS/qntAUaNM9CU+pZ/n4B0VWywNS8krJyIrxB3lduyDZ/o2S5sMSXJLKlMCXxm+qkdgdAc8XezQRo8N7/sSJSxRdCIg4rFP+Pfr2DcfH5I7GdbmVsJGthcN02kowBWJT/uKs0k3SzOGy+vRkC3ls8KamE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728393555; c=relaxed/simple; bh=YC9E3bvTJ7hN49WtkAHje9Qk2NVVPjrS7COHf2H/ZGI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dd0X+ZgN0vgHxOr/iogi8FaPGgJJZsYDj8AOdfxFvzIk0nndKx/8iSFlgj72i1prmgceQTCHwTgBOVXtEtB3YU9pfolXZ6nNcBw9T138Rird66SEjP47aWlnJYVmM5hbTo09xvk84NRIfbq0NILJs5bDI7by5t+zwWeoML0jtZI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dApZnxtL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dApZnxtL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FD3FC4CEC7; Tue, 8 Oct 2024 13:19:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728393555; bh=YC9E3bvTJ7hN49WtkAHje9Qk2NVVPjrS7COHf2H/ZGI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dApZnxtLMnt0YgJcB+w4GBmBp9WOvkLo1W6qPFwelPIAHcHNT3SvK7jBVFCmHG0mx mpV4w9wkHJ22kfYuzs0eGB2GQ5435bV6cQVyDKslAeQfghmXuA8dYwkUj/nrDvdUUg p0hkK7YRysPmvbhWM/u6afVMZRQQwbV/cfCFVJlM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuan-Wei Chiu , Andrii Nakryiko , Quentin Monnet , Sasha Levin Subject: [PATCH 6.6 185/386] bpftool: Fix undefined behavior in qsort(NULL, 0, ...) Date: Tue, 8 Oct 2024 14:07:10 +0200 Message-ID: <20241008115636.692458161@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241008115629.309157387@linuxfoundation.org> References: <20241008115629.309157387@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ 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 fd54ff436493f..28e9417a5c2e3 100644 --- a/tools/bpf/bpftool/net.c +++ b/tools/bpf/bpftool/net.c @@ -819,6 +819,9 @@ 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