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Sun, 13 Jun 2021 10:39:25 +0000 From: Sebastian Urban To: linux-bluetooth@vger.kernel.org Cc: Sebastian Urban Subject: [PATCH BlueZ] gatt-server: Flush notify multiple buffer when full and fix overflow Date: Sun, 13 Jun 2021 12:39:18 +0200 Message-Id: <20210613103918.5814-1-surban@surban.net> X-Mailer: git-send-email 2.25.1 In-Reply-To: <60c484e0.1c69fb81.c8dcd.c325@mx.google.com> References: <60c484e0.1c69fb81.c8dcd.c325@mx.google.com> X-Originating-IP: [24.134.128.129] X-ClientProxiedBy: ZR0P278CA0051.CHEP278.PROD.OUTLOOK.COM (2603:10a6:910:1d::20) To AM9P189MB1730.EURP189.PROD.OUTLOOK.COM (2603:10a6:20b:30c::17) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from dino.localdomain (24.134.128.129) by ZR0P278CA0051.CHEP278.PROD.OUTLOOK.COM (2603:10a6:910:1d::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4219.21 via Frontend Transport; Sun, 13 Jun 2021 10:39:24 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: a6807d19-35b4-4c86-5251-08d92e578331 X-MS-TrafficTypeDiagnostic: AM8P189MB1348: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:6430; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 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 X-OriginatorOrg: surban.net X-MS-Exchange-CrossTenant-Network-Message-Id: a6807d19-35b4-4c86-5251-08d92e578331 X-MS-Exchange-CrossTenant-AuthSource: AM9P189MB1730.EURP189.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Jun 2021 10:39:24.9398 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: a27af4ff-c4b3-4dec-be8d-845345d2ab67 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: GGkcNdhsMcnrmazUbojyQ4hKzD2oNUAwSxaU0GL8VuBtUO3vElKKU49Ug1VMrwka6A2bWzmMyym93gFaQwN9fg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM8P189MB1348 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org This fixes the calculation of available buffer space in bt_gatt_server_send_notification and sends pending notifications immediately when there is no more room to add a notification. Previously there was a buffer overflow caused by incorrect calculation of available buffer space: data->offset can equal data->len from a previous call to this function, leading (data->len - data->offset) to underflow after data->offset += 2. --- src/shared/gatt-server.c | 43 +++++++++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 7 deletions(-) diff --git a/src/shared/gatt-server.c b/src/shared/gatt-server.c index 970c35f94..dc4e681c9 100644 --- a/src/shared/gatt-server.c +++ b/src/shared/gatt-server.c @@ -1690,6 +1690,17 @@ static bool notify_multiple(void *user_data) return false; } +static bool notify_append_le16(struct nfy_mult_data *data, uint16_t value) +{ + if (data->offset + sizeof(value) > data->len) + return false; + + put_le16(value, data->pdu + data->offset); + data->offset += sizeof(value); + + return true; +} + bool bt_gatt_server_send_notification(struct bt_gatt_server *server, uint16_t handle, const uint8_t *value, uint16_t length, bool multiple) @@ -1700,23 +1711,35 @@ bool bt_gatt_server_send_notification(struct bt_gatt_server *server, if (!server || (length && !value)) return false; - if (multiple) + if (multiple) { data = server->nfy_mult; + /* flush buffered data if this request hits buffer size limit */ + if (data && data->offset > 0 && + data->len - data->offset < 4 + length) { + if (server->nfy_mult->id) + timeout_remove(server->nfy_mult->id); + notify_multiple(server); + /* data has been freed by notify_multiple */ + data = NULL; + } + } + if (!data) { data = new0(struct nfy_mult_data, 1); data->len = bt_att_get_mtu(server->att) - 1; data->pdu = malloc(data->len); } - put_le16(handle, data->pdu + data->offset); - data->offset += 2; - - length = MIN(data->len - data->offset, length); + if (!notify_append_le16(data, handle)) + goto error; if (multiple) { - put_le16(length, data->pdu + data->offset); - data->offset += 2; + length = MIN(data->len - data->offset - 2, length); + if (!notify_append_le16(data, length)) + goto error; + } else { + length = MIN(data->len - data->offset, length); } memcpy(data->pdu + data->offset, value, length); @@ -1740,6 +1763,12 @@ bool bt_gatt_server_send_notification(struct bt_gatt_server *server, free(data); return result; + +error: + if (data) + free(data); + + return false; } struct ind_data {