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[68.48.65.54]) by smtp.gmail.com with ESMTPSA id af79cd13be357-910bd8211e2sm562286785a.47.2026.05.15.07.38.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 May 2026 07:38:34 -0700 (PDT) From: Michael Bommarito To: Marcel Holtmann , Luiz Augusto von Dentz Cc: Daniel Winkler , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] Bluetooth: MGMT: validate Add Extended Advertising Data length Date: Fri, 15 May 2026 10:38:19 -0400 Message-ID: <20260515143819.1157807-1-michael.bommarito@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit MGMT_OP_ADD_EXT_ADV_DATA is registered as a variable-length command, with MGMT_ADD_EXT_ADV_DATA_SIZE as the fixed header size. The handler then uses cp->adv_data_len and cp->scan_rsp_len to validate and copy cp->data, but it never checks that those bytes are part of the mgmt command payload. A short command can therefore make add_ext_adv_data() pass an out-of-bounds pointer into tlv_data_is_valid(). If the bytes beyond the command buffer are addressable, they can also be copied into the advertising instance as scan response data, where the caller can read them back via MGMT_OP_GET_ADV_INSTANCE. The trigger requires CAP_NET_ADMIN in the initial user namespace; KASAN reports an 8-byte slab-out-of-bounds read. Reject commands whose length does not match the fixed header plus both advertising data lengths before parsing cp->data. Fixes: 12410572833a ("Bluetooth: Break add adv into two mgmt commands") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito --- net/bluetooth/mgmt.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c index b05bb380e5f8..de5bd6b637b2 100644 --- a/net/bluetooth/mgmt.c +++ b/net/bluetooth/mgmt.c @@ -9110,9 +9110,15 @@ static int add_ext_adv_data(struct sock *sk, struct hci_dev *hdev, void *data, struct adv_info *adv_instance; int err = 0; struct mgmt_pending_cmd *cmd; + u16 expected_len; BT_DBG("%s", hdev->name); + expected_len = struct_size(cp, data, cp->adv_data_len + cp->scan_rsp_len); + if (expected_len != data_len) + return mgmt_cmd_status(sk, hdev->id, MGMT_OP_ADD_EXT_ADV_DATA, + MGMT_STATUS_INVALID_PARAMS); + hci_dev_lock(hdev); adv_instance = hci_find_adv_instance(hdev, cp->instance); -- 2.53.0