From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 47CA6349AFF; Wed, 20 May 2026 17:47:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779299231; cv=none; b=mStbDLPoIcI2VAtKmYB5y023FhXgjxOmAnVjhH2FlZ9RBmBAZYmmu2ozhVXo7sef2pPnHnpBYTY+jqBe8leMJ38Cd59//vT45xX4BSXnpqs7i09FBsW92lvXA7J0cVVzG6WOcfml8ME0jQJDHIuk6Q0O2pdeTYeQO9swTk+dIyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779299231; c=relaxed/simple; bh=pV7go090PH0k+cUC4UfXSDFNVcUG8TfI5VonCB5w1/g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AxEYLRGXOjEyIiCRWvDEszW1Aye+iQoAGpbaKbi8vKVTtX8oAT9FUbOOALPGJci5/pcWJaQIhsbWaWeaRsAt6p6oM/N0fa8xywpXiSsL03dg0G8tIBDy9/qeMRDtDSCml+qtHAAOSsbcoNJ13g+eC2DWzQNAtBPxF1gWzLoaxGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LelmQjZ+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LelmQjZ+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B60451F000E9; Wed, 20 May 2026 17:47:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779299230; bh=mdViNADGup4CqCToRn4WCYed2ozDx2+Wek/Ki7rj4ac=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LelmQjZ+0gEBLKq9W2eQIrbFFZS9Qbm0w9H/snwNn5c4SRhFwW58kfMRqovIZYJWr YfwVZJjJvVJ/1PJ3Hr2bHWkkUYmFXCvA6y2eHkRjKrdSCfBsYglEUsUTmSsAr+wmom fG4rBNhYlxm1LPdO5uR0/CEc99Usb//AlftOaPq0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Weiming Shi , Florian Westphal , Pablo Neira Ayuso , Xiang Mei , Fernando Fernandez Mancera , Sasha Levin Subject: [PATCH 6.18 661/957] netfilter: nfnetlink_osf: fix divide-by-zero in OSF_WSS_MODULO Date: Wed, 20 May 2026 18:19:04 +0200 Message-ID: <20260520162148.867023812@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162134.554764788@linuxfoundation.org> References: <20260520162134.554764788@linuxfoundation.org> User-Agent: quilt/0.69 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei [ Upstream commit 2195574dc6d9017d32ac346987e12659f931d932 ] 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 Signed-off-by: Sasha Levin --- 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 9fc9544d4bc53..2305c7d9761eb 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; -- 2.53.0