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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cc72aefe72esm1372985a12.30.2026.09.19.15.17.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 15:17:39 -0700 (PDT) From: Hui Peng To: marcel@holtmann.org, luiz.dentz@gmail.com Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] Bluetooth: bnep: fix out-of-bounds reads on short RX/TX frames and control fallthrough Date: Sat, 19 Sep 2026 22:17:38 +0000 Message-ID: <20260919221738.3708655-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Fix multiple out-of-bounds reads in Bluetooth BNEP frame processing: 1. In bnep_rx_frame() and bnep_ctrl_frame() (net/bluetooth/bnep/core.c), use pskb_may_pull() to verify the BNEP header, control type byte, filter count, and extension headers exist before reading them, and return 0 after handling BNEP_CONTROL instead of falling through to Ethernet frame submission when no extension headers follow. 2. In bnep_net_xmit() (net/bluetooth/bnep/netdev.c), verify skb->len >= ETH_HLEN with pskb_may_pull() before reading the 14-byte Ethernet header to prevent an out-of-bounds heap read and infoleak on short AF_PACKET TX frames. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Assisted-by: LLM Signed-off-by: Hui Peng --- diff --git a/net/bluetooth/bnep/core.c b/net/bluetooth/bnep/core.c index f7d88c33e23e..ad24d2486665 100644 --- a/net/bluetooth/bnep/core.c +++ b/net/bluetooth/bnep/core.c @@ -270,9 +270,14 @@ static int bnep_rx_extension(struct bnep_session *s, struct sk_buff *skb) BT_DBG("type 0x%x len %u", h->type, h->len); + if (skb->len < h->len) { + err = -EILSEQ; + break; + } + switch (h->type & BNEP_TYPE_MASK) { case BNEP_EXT_CONTROL: - bnep_rx_control(s, skb->data, skb->len); + bnep_rx_control(s, skb->data, h->len); break; default: @@ -373,6 +378,11 @@ static int bnep_rx_frame(struct bnep_session *s, struct sk_buff *skb) goto badframe; } + if ((type & BNEP_TYPE_MASK) == BNEP_CONTROL) { + kfree_skb(skb); + return 0; + } + /* Strip 802.1p header */ if (ntohs(s->eh.h_proto) == ETH_P_8021Q) { if (!skb_pull(skb, 4)) @@ -451,6 +461,11 @@ static int bnep_tx_frame(struct bnep_session *s, struct sk_buff *skb) goto send; } + if (skb->len < ETH_HLEN) { + kfree_skb(skb); + return 0; + } + iv[il++] = (struct kvec) { &type, 1 }; len++; diff --git a/net/bluetooth/bnep/netdev.c b/net/bluetooth/bnep/netdev.c index ee1e39a3daff..b451ef457741 100644 --- a/net/bluetooth/bnep/netdev.c +++ b/net/bluetooth/bnep/netdev.c @@ -166,6 +166,12 @@ static netdev_tx_t bnep_net_xmit(struct sk_buff *skb, BT_DBG("skb %p, dev %p", skb, dev); + if (!pskb_may_pull(skb, ETH_HLEN)) { + dev->stats.tx_dropped++; + kfree_skb(skb); + return NETDEV_TX_OK; + } + #ifdef CONFIG_BT_BNEP_MC_FILTER if (bnep_net_mc_filter(skb, s)) { kfree_skb(skb); @@ -218,7 +224,7 @@ void bnep_net_setup(struct net_device *dev) dev->addr_len = ETH_ALEN; ether_setup(dev); - dev->min_mtu = 0; + dev->min_mtu = ETH_MIN_MTU; dev->max_mtu = ETH_MAX_MTU; dev->priv_flags &= ~IFF_TX_SKB_SHARING; dev->netdev_ops = &bnep_netdev_ops;