From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (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 EC7DF3BED27; Thu, 16 Apr 2026 13:15:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776345306; cv=none; b=V7Vry5o8yUyMU70YQRL+Oku90ZLwB1ApwKBUcrlO9EveA9Uv169j0xsO3qfWCVi0luD1DQ2MGfQXYAcQLEqI9hxDK5SsgBcYU8zJm1CvM8j57UzRffwCx8IM/XKlRE9+xmgghiO8MkQ/sf77mo3ANdVzJuoS05h59AvAzNuMv0Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776345306; c=relaxed/simple; bh=PawOKsjU/i0MTF68zbUb+VsSAv0gXGWmxITDx7vkR6k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Paqk+g05La910l4NFaLs1aFTSEcYzyvo1VKU61Vx8Wa7NhCSZf1OR4pJ/37uiGDMr5lasO3/BF0aVa/Oh9p2Gk7Fcls8gxs/v9va5cssl9yvlQ741MkkdpUZQJLBQwXeTRm5ktEh9J7g58TJabmg1UN5inBZOEWjUw3h9IEzSY8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=q/tY4Ymt; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="q/tY4Ymt" Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id E8F7160254; Thu, 16 Apr 2026 15:15:02 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1776345303; bh=0HS0505hGdVF8P/vAEeHwqgAoOpv+wYp7KMbrpsv3RI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q/tY4YmtWtu3tiAWQgARW4zma2O51HrPHWZ9vjqqRcI6pRX+fI7jC4HmxDRpwnfLv adcgNZZ3MDl+VElE/AjXf1DBPfvpaF5toZofiSrlzdQUNMlXGJBCk30ASXAtAz4MDD SrPvIU83124MQR+gMp0VBKAG10ZKzFABTOSLVOtWpzNhfsP3+hPZLVh/RUCW9j8d1Y w8UkvAbhnWbcAh+v7dW81m+GZluelAt9qL6CtRrpXhVZr6Mr9QtBSZUItZLXLXJf9n adGBngCO+KVrsdASBYC7jfgg6aebxQJwbnk54+NSjglRPBlDupDVnQG9y4D2ChpwiQ VKu36l1yd7Sww== From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de, horms@kernel.org Subject: [PATCH net 02/11] netfilter: nfnetlink_osf: fix divide-by-zero in OSF_WSS_MODULO Date: Thu, 16 Apr 2026 15:14:44 +0200 Message-ID: <20260416131453.308611-3-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260416131453.308611-1-pablo@netfilter.org> References: <20260416131453.308611-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Xiang Mei nf_osf_match_one() computes ctx->window % f->wss.val in the OSF_WSS_MODULO branch with no guard for f->wss.val == 0. A CAP_NET_ADMIN user can add such a fingerprint via nfnetlink; a subsequent matching TCP SYN divides by zero and panics the kernel. Reject the bogus fingerprint in nfnl_osf_add_callback() above the per-option for-loop. f->wss is per-fingerprint, not per-option, so the check must run regardless of f->opt_num (including 0). Also reject wss.wc >= OSF_WSS_MAX; nf_osf_match_one() already treats that as "should not happen". Crash: Oops: divide error: 0000 [#1] SMP KASAN NOPTI RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98) Call Trace: nf_osf_match (net/netfilter/nfnetlink_osf.c:220) xt_osf_match_packet (net/netfilter/xt_osf.c:32) ipt_do_table (net/ipv4/netfilter/ip_tables.c:348) nf_hook_slow (net/netfilter/core.c:622) ip_local_deliver (net/ipv4/ip_input.c:265) ip_rcv (include/linux/skbuff.h:1162) __netif_receive_skb_one_core (net/core/dev.c:6181) process_backlog (net/core/dev.c:6642) __napi_poll (net/core/dev.c:7710) net_rx_action (net/core/dev.c:7945) handle_softirqs (kernel/softirq.c:622) Fixes: 11eeef41d5f6 ("netfilter: passive OS fingerprint xtables match") Reported-by: Weiming Shi Suggested-by: Florian Westphal Suggested-by: Pablo Neira Ayuso Signed-off-by: Xiang Mei Reviewed-by: Fernando Fernandez Mancera Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nfnetlink_osf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c index 45d9ad231a92..70172ca07858 100644 --- a/net/netfilter/nfnetlink_osf.c +++ b/net/netfilter/nfnetlink_osf.c @@ -320,6 +320,10 @@ static int nfnl_osf_add_callback(struct sk_buff *skb, if (f->opt_num > ARRAY_SIZE(f->opt)) return -EINVAL; + if (f->wss.wc >= OSF_WSS_MAX || + (f->wss.wc == OSF_WSS_MODULO && f->wss.val == 0)) + return -EINVAL; + for (i = 0; i < f->opt_num; i++) { if (!f->opt[i].length || f->opt[i].length > MAX_IPOPTLEN) return -EINVAL; -- 2.47.3