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 EF471349AE0; Thu, 2 Jul 2026 16:53:24 +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=1783011206; cv=none; b=jH2QEaI2NKTGLNPEnkODOtZfJVAeU31nGXF9OJIlsc7MjTlTeMAhwSTXsW3xVG2Ap0KnTvI9aSls3cL5Q2LeM2epkoqgUftpH2hOPJBpKUDkA76f5hqVWERDeU/k04qQmFJLqjb9UWIe1LuzyLzUPWQdfD+nAODx4uShQGqQzrU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783011206; c=relaxed/simple; bh=0LGjITDWofpE4KMHiUaNODSK2BOSono7ldjSjTvHhuE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MqcwDsilKot63gY0uVAyuU16kzjnOfHc4pl/tRifzqIA3KoYuLn4HHeo16poyZxaG6NwgLEq7Jg1Kag7ZDmgetiK1POCbGO1pZVD3NUDSX1uUNX/BFgrn8xbsWGrReG6G7NjT6hC7z3B4tlTVgKY/h8dquzwqGjWxCYhrdeWTbc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ll0OXPqS; 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="ll0OXPqS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6165F1F000E9; Thu, 2 Jul 2026 16:53:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783011204; bh=H4Q0132fLj/JvOi7YcW9huE/JmspasofxI2u4k/EpHY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ll0OXPqSroIOnXPL7rBWZ2TmhBsFAsG3cFkllfyooOzH1ndbhPgMTp+g3QKDVdMxK CXPEy/AiVn3m4yG4IDDL9XZZqEPOXmmeXqNr4+ERCH86ZTYa0gqelx8yFrn2L/Eewa cEV1hWtf0oi/uew1+KXq6kJNUJXBAmgdwuEq76hA= 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 6.18 020/108] batman-adv: frag: ensure fragment is writable before modifying TTL Date: Thu, 2 Jul 2026 18:20:17 +0200 Message-ID: <20260702155112.527444348@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 b7293c6e8c15b2db77809b25cf8389e35331b27a upstream. Before batman-adv is allowed to write to an skb, it either has to have its own copy of the skb or use skb_cow() to ensure that the data part is not shared. But batadv_frag_skb_fwd() modifies the TTL even when it is shared. Adding a skb_cow() right before this operation avoids this and can at the same time prepare it for the modifications required to forward the fragment. 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 | 15 ++++++++++++++- net/batman-adv/fragmentation.h | 3 ++- net/batman-adv/routing.c | 3 +-- 3 files changed, 17 insertions(+), 4 deletions(-) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index 31395281692cb5..ffa5d4b0740959 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -384,6 +384,8 @@ bool batadv_frag_skb_buffer(struct sk_buff **skb, * @skb: skb to forward * @recv_if: interface that the skb is received on * @orig_node_src: originator that the skb is received from + * @rx_result: set to NET_RX_SUCCESS when the fragment was forwarded and + * NET_RX_DROP when it was dropped; only valid when true is returned * * Look up the next-hop of the fragments payload and check if the merged packet * will exceed the MTU towards the next-hop. If so, the fragment is forwarded @@ -393,7 +395,8 @@ bool batadv_frag_skb_buffer(struct sk_buff **skb, */ bool batadv_frag_skb_fwd(struct sk_buff *skb, struct batadv_hard_iface *recv_if, - struct batadv_orig_node *orig_node_src) + struct batadv_orig_node *orig_node_src, + int *rx_result) { struct batadv_priv *bat_priv = netdev_priv(recv_if->mesh_iface); struct batadv_neigh_node *neigh_node = NULL; @@ -412,12 +415,22 @@ 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 (skb_cow(skb, ETH_HLEN) < 0) { + kfree_skb(skb); + *rx_result = NET_RX_DROP; + ret = true; + goto out; + } + + packet = (struct batadv_frag_packet *)skb->data; + batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_FWD); batadv_add_counter(bat_priv, BATADV_CNT_FRAG_FWD_BYTES, skb->len + ETH_HLEN); packet->ttl--; batadv_send_unicast_skb(skb, neigh_node); + *rx_result = NET_RX_SUCCESS; ret = true; } diff --git a/net/batman-adv/fragmentation.h b/net/batman-adv/fragmentation.h index dbf0871f870303..51e281027ab630 100644 --- a/net/batman-adv/fragmentation.h +++ b/net/batman-adv/fragmentation.h @@ -19,7 +19,8 @@ void batadv_frag_purge_orig(struct batadv_orig_node *orig, bool (*check_cb)(struct batadv_frag_table_entry *)); bool batadv_frag_skb_fwd(struct sk_buff *skb, struct batadv_hard_iface *recv_if, - struct batadv_orig_node *orig_node_src); + struct batadv_orig_node *orig_node_src, + int *rx_result); bool batadv_frag_skb_buffer(struct sk_buff **skb, struct batadv_orig_node *orig_node); int batadv_frag_send_packet(struct sk_buff *skb, diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index cdcea90db61235..4483f8d9c75831 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -1168,10 +1168,9 @@ int batadv_recv_frag_packet(struct sk_buff *skb, /* Route the fragment if it is not for us and too big to be merged. */ if (!batadv_is_my_mac(bat_priv, frag_packet->dest) && - batadv_frag_skb_fwd(skb, recv_if, orig_node_src)) { + batadv_frag_skb_fwd(skb, recv_if, orig_node_src, &ret)) { /* skb was consumed */ skb = NULL; - ret = NET_RX_SUCCESS; goto put_orig_node; } -- 2.53.0