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[Backport v3.3-branch] bluetooth: cgms: racp: validate write length #28594

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Merged
rlubos merged 1 commit into from
May 12, 2026
Merged

[Backport v3.3-branch] bluetooth: cgms: racp: validate write length #28594

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8 changes: 8 additions & 0 deletions subsys/bluetooth/services/cgms/cgms.c
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Original file line number Diff line number Diff line change
Expand Up @@ -269,6 +269,14 @@ static ssize_t racp_on_receive(struct bt_conn *conn,
{
int rc;

if (offset != 0) {
return BT_GATT_ERR(BT_ATT_ERR_INVALID_OFFSET);
}

if (len > CGMS_RACP_MAX_LENGTH) {
return BT_GATT_ERR(BT_ATT_ERR_INVALID_ATTRIBUTE_LEN);
}

rc = cgms_racp_recv_request(conn, buf, len);
if (rc < 0) {
LOG_WRN("Internal Error during RACP Handling: %d", rc);
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3 changes: 3 additions & 0 deletions subsys/bluetooth/services/cgms/cgms_internal.h
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Expand Up @@ -15,6 +15,9 @@
extern "C" {
#endif

/* Maximum byte length of a RACP characteristic write. */
#define CGMS_RACP_MAX_LENGTH 20

/* Continuous Glucose Monitoring feature */
enum cgms_feat {
CGMS_FEAT_CALIBRATION_SUPPORTED = BIT(0),
Expand Down
14 changes: 8 additions & 6 deletions subsys/bluetooth/services/cgms/cgms_racp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,6 @@

LOG_MODULE_DECLARE(cgms, CONFIG_BT_CGMS_LOG_LEVEL);

#define CGMS_RACP_LENGTH 20

#define RACP_Q_STACK_SIZE 2048
#define RACP_Q_PRIORITY 1
K_THREAD_STACK_DEFINE(racp_q_stack_area, RACP_Q_STACK_SIZE);
Expand Down Expand Up @@ -79,7 +77,7 @@ struct racp_task {
struct k_work item;
struct bt_conn *peer;
struct net_buf_simple req;
uint8_t req_buf[CGMS_RACP_LENGTH];
uint8_t req_buf[CGMS_RACP_MAX_LENGTH];
};

static struct cgms_meas_db_entry cgms_meas_db_entry_pool[RECORD_NUM];
Expand All @@ -105,7 +103,7 @@ static struct cgms_meas_db_entry *entry_alloc(void)

static int generic_handler(struct bt_conn *peer, uint8_t opcode, uint8_t response_code)
{
NET_BUF_SIMPLE_DEFINE(rsp, CGMS_RACP_LENGTH);
NET_BUF_SIMPLE_DEFINE(rsp, CGMS_RACP_MAX_LENGTH);

net_buf_simple_add_u8(&rsp, RACP_OPCODE_RESPONSE_CODE);
net_buf_simple_add_u8(&rsp, RACP_OPERATOR_NULL);
Expand Down Expand Up @@ -273,7 +271,7 @@ static int report_num_recs_all_handler(struct bt_conn *peer)
uint16_t count = 0;
sys_snode_t *record_node;

NET_BUF_SIMPLE_DEFINE(rsp, CGMS_RACP_LENGTH);
NET_BUF_SIMPLE_DEFINE(rsp, CGMS_RACP_MAX_LENGTH);

if (!sys_slist_is_empty(&database)) {
SYS_SLIST_FOR_EACH_NODE(&database, record_node) {
Expand All @@ -297,7 +295,7 @@ static int report_num_recs_greater_or_equal_handler(struct bt_conn *peer,
struct cgms_meas_db_entry *entry;
sys_snode_t *record_node;

NET_BUF_SIMPLE_DEFINE(rsp, CGMS_RACP_LENGTH);
NET_BUF_SIMPLE_DEFINE(rsp, CGMS_RACP_MAX_LENGTH);

if (operand->len < 3) {
return generic_handler(peer, RACP_OPCODE_REPORT_RECS,
Expand Down Expand Up @@ -434,6 +432,10 @@ int cgms_racp_recv_request(struct bt_conn *peer, const uint8_t *req_data, uint16
}

/* For other requests, prepare the data and submit to workqueue. */
if (req_len > sizeof(report_record_task.req_buf)) {
return -EMSGSIZE;
}

report_record_task.peer = peer;
memcpy(report_record_task.req_buf, req_data, req_len);
net_buf_simple_init_with_data(&report_record_task.req, report_record_task.req_buf, req_len);
Expand Down
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