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 9234B26F46F; Thu, 2 Jul 2026 16:53:27 +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=1783011208; cv=none; b=BQVs76ivS07Vdzj1Tcc70GA1kQBTVxug0eGMsgNZekL0OeWXNSMDDLa+CPxcw05XOahl7P8sntfEdx+iOEHypo8p2HPkztgh0gyVX5h3xbKZcYm4EdwPXKRDoEbfYkvYzlhG/dxaXoRFuFJJ+XX6vZgdxd+Z7pqBASh3CrMRSJE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783011208; c=relaxed/simple; bh=tuc0o2bqUDuG1hVMWHoAn5I0r/L3cT3umShTTvraBYc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q7pdgYq6Xj3gn/wHONjZDoIGQhdmWgrEK54krCFULeyu3uZgXhJosAOibYOE9Gl+gFqhuimq0rayLe95tnBASO6fZn37ytSlljwaph++JS96vs3ZDmmEa6uii5n9Utg1p411xKfirWmro7bTJIZjRZyJfXsVhsQqCqbUZ7rrCx0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=s9jH8vE0; 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="s9jH8vE0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04EE81F000E9; Thu, 2 Jul 2026 16:53:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783011207; bh=vI+6KJs8ZgzDsLzgrFVLvy9G8dOKgyvZLyKNxRx+G9I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=s9jH8vE0Z3An1CuJ0QhXKoU8Tqhqcskz1wnA7sEi4Bjjees6e8EQJTMhcYLpkRZQR +jQSW0dSZq+I1O1PiH4gPAswUBsHG0CF4RHnek9tAx18lhBMVuvuMbfWpzNgKisT+Z lUhlgGywOW7eme9lFNNlKX2fVmbR3r843KEPDYPg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Sven Eckelmann , Sasha Levin Subject: [PATCH 6.18 021/108] batman-adv: frag: avoid underflow of TTL Date: Thu, 2 Jul 2026 18:20:18 +0200 Message-ID: <20260702155112.548911921@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155112.110058792@linuxfoundation.org> References: <20260702155112.110058792@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: Sven Eckelmann commit 493d9d2528e1a09b090e4b37f0f553def7bd5ce9 upstream. Packets with a TTL are using it to limit the amount of time this packet can be forwarded. But for batadv_frag_packet, the TTL was always only reduced but it was never evaluated. It could even underflow without any effect. Check the TTL in batadv_frag_skb_fwd() before attempting to prepare it for forwarding. This keeps it in sync with the not fragmented unicast packet. Cc: stable@kernel.org Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge") Signed-off-by: Sven Eckelmann Signed-off-by: Sasha Levin --- net/batman-adv/fragmentation.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index ffa5d4b0740959..4779741e7273ea 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -415,6 +415,13 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb, */ total_size = ntohs(packet->total_size); if (total_size > neigh_node->if_incoming->net_dev->mtu) { + if (packet->ttl < 2) { + kfree_skb(skb); + *rx_result = NET_RX_DROP; + ret = true; + goto out; + } + if (skb_cow(skb, ETH_HLEN) < 0) { kfree_skb(skb); *rx_result = NET_RX_DROP; -- 2.53.0