From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793209794; b=Rh6zmxzGItqzegcZ19aD3gAYMu+By2ocVuRcfybq0FcOmSI1U7HhwMQu9XgLvGuZjG5L D5pXcW3FmpXxnckwF/XW6x8Pu9Wgvu7U3YE0VH750z+XCVU8CTQo8/5yRArkaUaydTbl7 hJsuC0sDtEgjgCogrVJqN1i0aaoSDB7XJrGybpzSmlzm7LZbq7bDb1nN0Sk/T+IhWf3SO kbUovHePxoG3qI4Ix/l/TnUrf6FoJLzOK5uAvtBBaLTXNU5Uco28xfSc3eVdFTnCxy+YY 4xorQwoVHJuC1vbjAZolKNZkU8MJV6Gepjln8JZrdXNxHeNVX2ORyLAwdb0J1wASXeA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793209794; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=KIH/rsYprcwNPb/Kfl3G8c0NMjM7yK+KjZ/qqtzciHc=; b=EOZX+EeI5l9PfV2HfdkTQqC42nWl+pVN1gSG9DYpzqLVMo2hPIn+NVIY/bGOu3L+9nBv 4w4z6BLe05nPQqRmGykIlj3OJusJAXnv5qCMD/ruDjMSceyk4fiPdCIk5CLJaDAdPamJm OuAHYQr71RQHlMaZywMEYTPIt4ONhmqcafwKcELHkmhkH5VgO8lzO/d2374v1oGfzdVIW ENXvyAp+ippQ4KaAlu77eAgfN3t9Q0XY6p5oyX9pf8UsId++qRky4KKNNremdB/7IJpP2 B2p+k72YollUiIwMytW9ygsEGpQ2edO8IJg3tMmCzGzcJSbjrEIVx8vBFPt+KTaT/yQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="rSY/GkvO"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5B1B606A31A; Wed, 28 Oct 2026 17:49:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=rSY/GkvO Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C8601F01825; Wed, 28 Oct 2026 17:49:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793209793; bh=KIH/rsYprcwNPb/Kfl3G8c0NMjM7yK+KjZ/qqtzciHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rSY/GkvOnzTwHziMBE44FEfR9RBcteOlFilulA1urcd6aR0aagm7jOq6rIFWO0FuM FiXsmeQXXv2u6qIthvx//1HOhIHHxU63J41osYK7G5ILhOor+YUDfsLyf+hZVP6WoK Ax4c+y0qm9gCp/zKFKDLuYBj6N3vlXOMkghTyb90= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vega , Luxing Yin , Zihan Xi , Willem de Bruijn , Paolo Abeni , Ting-Han Hou Subject: [PATCH 6.18 042/109] net: gso: limit recursive IP-in-IP segmentation Date: Wed, 28 Oct 2026 18:00:26 +0100 Message-ID: <20261028165943.352531631@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.357251485@linuxfoundation.org> References: <20261028165942.357251485@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zihan Xi commit 006c8b834aed8b02bd8fb9fb05e9e7ead37d1763 upstream. IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment() for each nested IP header. encap_level tracks header bytes, not callback depth, so a deep chain can exhaust the kernel stack. Making inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP GSO/TSO later made the path reachable. The IPv6 stackable path was introduced separately and uses the same guard. Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once per top-level GSO operation and preserved across GRE/UDP context changes. Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first five entries pass, and the sixth returns -EINVAL before dispatching another GSO callback. Fixes: 3347c9602955 ("ipv4: gso: make inet_gso_segment() stackable") Cc: stable@vger.kernel.org Reported-by: Vega Closes: https://lore.kernel.org/all/cover.1790157745.git.zihanx@nebusec.ai/ Assisted-by: LLM Co-developed-by: Luxing Yin Signed-off-by: Luxing Yin Signed-off-by: Zihan Xi Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260924051521.32568-2-zihanx@nebusec.ai Signed-off-by: Paolo Abeni [ Ting-Han: ipv6_gso_segment() still calls ipv6_hopopt_jumbo_remove() right after skb_reset_network_header() in this version; keep the new recursion check directly after skb_reset_network_header() as upstream does, before the jumbo removal ] Signed-off-by: Ting-Han Hou Signed-off-by: Greg Kroah-Hartman --- include/net/gso.h | 8 ++++++++ net/core/gso.c | 1 + net/ipv4/af_inet.c | 3 +++ net/ipv6/ip6_offload.c | 4 ++++ 4 files changed, 16 insertions(+) --- a/include/net/gso.h +++ b/include/net/gso.h @@ -19,10 +19,18 @@ struct skb_gso_cb { int encap_level; __wsum csum; __u16 csum_start; + /* Number of IPv4/IPv6 GSO handler entries for this packet. */ + u8 recursion_counter; }; #define SKB_GSO_CB_OFFSET 32 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET)) +static inline bool gso_recursion_inc_test(struct sk_buff *skb, + unsigned int limit) +{ + return ++SKB_GSO_CB(skb)->recursion_counter > limit; +} + static inline int skb_tnl_header_len(const struct sk_buff *inner_skb) { return (skb_mac_header(inner_skb) - inner_skb->head) - --- a/net/core/gso.c +++ b/net/core/gso.c @@ -117,6 +117,7 @@ struct sk_buff *__skb_gso_segment(struct SKB_GSO_CB(skb)->mac_offset = skb_headroom(skb); SKB_GSO_CB(skb)->encap_level = 0; + SKB_GSO_CB(skb)->recursion_counter = 0; skb_reset_mac_header(skb); skb_reset_mac_len(skb); --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1364,6 +1364,9 @@ struct sk_buff *inet_gso_segment(struct int id; skb_reset_network_header(skb); + if (unlikely(gso_recursion_inc_test(skb, + IP_TUNNEL_RECURSION_LIMIT))) + goto out; nhoff = skb_network_header(skb) - skb_mac_header(skb); if (unlikely(!pskb_may_pull(skb, sizeof(*iph)))) goto out; --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "ip6_offload.h" @@ -120,6 +121,9 @@ static struct sk_buff *ipv6_gso_segment( bool gso_partial; skb_reset_network_header(skb); + if (unlikely(gso_recursion_inc_test(skb, + IP_TUNNEL_RECURSION_LIMIT))) + goto out; err = ipv6_hopopt_jumbo_remove(skb); if (err) return ERR_PTR(err);