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Bluetooth: Properly check L2CAP config option output buffer length

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Validate the output buffer length for L2CAP config requests and responses
to avoid overflowing the stack buffer used for building the option blocks.

Cc: stable@vger.kernel.org
Signed-off-by: Ben Seri <ben@armis.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ben Seri 2017-09-09 23:15:59 +02:00 committed by Linus Torvalds
parent 4dfc278803
commit e860d2c904
1 changed files with 43 additions and 37 deletions
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80
net/bluetooth/l2cap_core.c
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@ -58,7 +58,7 @@ static struct sk_buff *l2cap_build_cmd(struct l2cap_conn *conn,
u8 code, u8 ident, u16 dlen, void *data); u8 code, u8 ident, u16 dlen, void *data);
static void l2cap_send_cmd(struct l2cap_conn *conn, u8 ident, u8 code, u16 len, static void l2cap_send_cmd(struct l2cap_conn *conn, u8 ident, u8 code, u16 len,
void *data); void *data);
static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data); static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data, size_t data_size);
static void l2cap_send_disconn_req(struct l2cap_chan *chan, int err); static void l2cap_send_disconn_req(struct l2cap_chan *chan, int err);
static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control, static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
@ -1473,7 +1473,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
set_bit(CONF_REQ_SENT, &chan->conf_state); set_bit(CONF_REQ_SENT, &chan->conf_state);
l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ, l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, buf), buf); l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
chan->num_conf_req++; chan->num_conf_req++;
} }
@ -2987,12 +2987,15 @@ static inline int l2cap_get_conf_opt(void **ptr, int *type, int *olen,
return len; return len;
} }
static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val) static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val, size_t size)
{ {
struct l2cap_conf_opt *opt = *ptr; struct l2cap_conf_opt *opt = *ptr;
BT_DBG("type 0x%2.2x len %u val 0x%lx", type, len, val); BT_DBG("type 0x%2.2x len %u val 0x%lx", type, len, val);
if (size < L2CAP_CONF_OPT_SIZE + len)
return;
opt->type = type; opt->type = type;
opt->len = len; opt->len = len;
@ -3017,7 +3020,7 @@ static void l2cap_add_conf_opt(void **ptr, u8 type, u8 len, unsigned long val)
*ptr += L2CAP_CONF_OPT_SIZE + len; *ptr += L2CAP_CONF_OPT_SIZE + len;
} }
static void l2cap_add_opt_efs(void **ptr, struct l2cap_chan *chan) static void l2cap_add_opt_efs(void **ptr, struct l2cap_chan *chan, size_t size)
{ {
struct l2cap_conf_efs efs; struct l2cap_conf_efs efs;
@ -3045,7 +3048,7 @@ static void l2cap_add_opt_efs(void **ptr, struct l2cap_chan *chan)
} }
l2cap_add_conf_opt(ptr, L2CAP_CONF_EFS, sizeof(efs), l2cap_add_conf_opt(ptr, L2CAP_CONF_EFS, sizeof(efs),
(unsigned long) &efs); (unsigned long) &efs, size);
} }
static void l2cap_ack_timeout(struct work_struct *work) static void l2cap_ack_timeout(struct work_struct *work)
@ -3191,11 +3194,12 @@ static inline void l2cap_txwin_setup(struct l2cap_chan *chan)
chan->ack_win = chan->tx_win; chan->ack_win = chan->tx_win;
} }
static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data) static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data, size_t data_size)
{ {
struct l2cap_conf_req *req = data; struct l2cap_conf_req *req = data;
struct l2cap_conf_rfc rfc = { .mode = chan->mode }; struct l2cap_conf_rfc rfc = { .mode = chan->mode };
void *ptr = req->data; void *ptr = req->data;
void *endptr = data + data_size;
u16 size; u16 size;
BT_DBG("chan %p", chan); BT_DBG("chan %p", chan);
@ -3220,7 +3224,7 @@ static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data)
done: done:
if (chan->imtu != L2CAP_DEFAULT_MTU) if (chan->imtu != L2CAP_DEFAULT_MTU)
l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu); l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu, endptr - ptr);
switch (chan->mode) { switch (chan->mode) {
case L2CAP_MODE_BASIC: case L2CAP_MODE_BASIC:
@ -3239,7 +3243,7 @@ done:
rfc.max_pdu_size = 0; rfc.max_pdu_size = 0;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc), l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
(unsigned long) &rfc); (unsigned long) &rfc, endptr - ptr);
break; break;
case L2CAP_MODE_ERTM: case L2CAP_MODE_ERTM:
@ -3259,21 +3263,21 @@ done:
L2CAP_DEFAULT_TX_WINDOW); L2CAP_DEFAULT_TX_WINDOW);
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc), l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
(unsigned long) &rfc); (unsigned long) &rfc, endptr - ptr);
if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) if (test_bit(FLAG_EFS_ENABLE, &chan->flags))
l2cap_add_opt_efs(&ptr, chan); l2cap_add_opt_efs(&ptr, chan, endptr - ptr);
if (test_bit(FLAG_EXT_CTRL, &chan->flags)) if (test_bit(FLAG_EXT_CTRL, &chan->flags))
l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2, l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2,
chan->tx_win); chan->tx_win, endptr - ptr);
if (chan->conn->feat_mask & L2CAP_FEAT_FCS) if (chan->conn->feat_mask & L2CAP_FEAT_FCS)
if (chan->fcs == L2CAP_FCS_NONE || if (chan->fcs == L2CAP_FCS_NONE ||
test_bit(CONF_RECV_NO_FCS, &chan->conf_state)) { test_bit(CONF_RECV_NO_FCS, &chan->conf_state)) {
chan->fcs = L2CAP_FCS_NONE; chan->fcs = L2CAP_FCS_NONE;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1, l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1,
chan->fcs); chan->fcs, endptr - ptr);
} }
break; break;
@ -3291,17 +3295,17 @@ done:
rfc.max_pdu_size = cpu_to_le16(size); rfc.max_pdu_size = cpu_to_le16(size);
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc), l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
(unsigned long) &rfc); (unsigned long) &rfc, endptr - ptr);
if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) if (test_bit(FLAG_EFS_ENABLE, &chan->flags))
l2cap_add_opt_efs(&ptr, chan); l2cap_add_opt_efs(&ptr, chan, endptr - ptr);
if (chan->conn->feat_mask & L2CAP_FEAT_FCS) if (chan->conn->feat_mask & L2CAP_FEAT_FCS)
if (chan->fcs == L2CAP_FCS_NONE || if (chan->fcs == L2CAP_FCS_NONE ||
test_bit(CONF_RECV_NO_FCS, &chan->conf_state)) { test_bit(CONF_RECV_NO_FCS, &chan->conf_state)) {
chan->fcs = L2CAP_FCS_NONE; chan->fcs = L2CAP_FCS_NONE;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1, l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1,
chan->fcs); chan->fcs, endptr - ptr);
} }
break; break;
} }
@ -3312,10 +3316,11 @@ done:
return ptr - data; return ptr - data;
} }
static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data) static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data, size_t data_size)
{ {
struct l2cap_conf_rsp *rsp = data; struct l2cap_conf_rsp *rsp = data;
void *ptr = rsp->data; void *ptr = rsp->data;
void *endptr = data + data_size;
void *req = chan->conf_req; void *req = chan->conf_req;
int len = chan->conf_len; int len = chan->conf_len;
int type, hint, olen; int type, hint, olen;
@ -3417,7 +3422,7 @@ done:
return -ECONNREFUSED; return -ECONNREFUSED;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc), l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
(unsigned long) &rfc); (unsigned long) &rfc, endptr - ptr);
} }
if (result == L2CAP_CONF_SUCCESS) { if (result == L2CAP_CONF_SUCCESS) {
@ -3430,7 +3435,7 @@ done:
chan->omtu = mtu; chan->omtu = mtu;
set_bit(CONF_MTU_DONE, &chan->conf_state); set_bit(CONF_MTU_DONE, &chan->conf_state);
} }
l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->omtu); l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->omtu, endptr - ptr);
if (remote_efs) { if (remote_efs) {
if (chan->local_stype != L2CAP_SERV_NOTRAFIC && if (chan->local_stype != L2CAP_SERV_NOTRAFIC &&
@ -3444,7 +3449,7 @@ done:
l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS,
sizeof(efs), sizeof(efs),
(unsigned long) &efs); (unsigned long) &efs, endptr - ptr);
} else { } else {
/* Send PENDING Conf Rsp */ /* Send PENDING Conf Rsp */
result = L2CAP_CONF_PENDING; result = L2CAP_CONF_PENDING;
@ -3477,7 +3482,7 @@ done:
set_bit(CONF_MODE_DONE, &chan->conf_state); set_bit(CONF_MODE_DONE, &chan->conf_state);
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
sizeof(rfc), (unsigned long) &rfc); sizeof(rfc), (unsigned long) &rfc, endptr - ptr);
if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) { if (test_bit(FLAG_EFS_ENABLE, &chan->flags)) {
chan->remote_id = efs.id; chan->remote_id = efs.id;
@ -3491,7 +3496,7 @@ done:
le32_to_cpu(efs.sdu_itime); le32_to_cpu(efs.sdu_itime);
l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS,
sizeof(efs), sizeof(efs),
(unsigned long) &efs); (unsigned long) &efs, endptr - ptr);
} }
break; break;
@ -3505,7 +3510,7 @@ done:
set_bit(CONF_MODE_DONE, &chan->conf_state); set_bit(CONF_MODE_DONE, &chan->conf_state);
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc), l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
(unsigned long) &rfc); (unsigned long) &rfc, endptr - ptr);
break; break;
@ -3527,10 +3532,11 @@ done:
} }
static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
void *data, u16 *result) void *data, size_t size, u16 *result)
{ {
struct l2cap_conf_req *req = data; struct l2cap_conf_req *req = data;
void *ptr = req->data; void *ptr = req->data;
void *endptr = data + size;
int type, olen; int type, olen;
unsigned long val; unsigned long val;
struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC }; struct l2cap_conf_rfc rfc = { .mode = L2CAP_MODE_BASIC };
@ -3548,13 +3554,13 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
chan->imtu = L2CAP_DEFAULT_MIN_MTU; chan->imtu = L2CAP_DEFAULT_MIN_MTU;
} else } else
chan->imtu = val; chan->imtu = val;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu); l2cap_add_conf_opt(&ptr, L2CAP_CONF_MTU, 2, chan->imtu, endptr - ptr);
break; break;
case L2CAP_CONF_FLUSH_TO: case L2CAP_CONF_FLUSH_TO:
chan->flush_to = val; chan->flush_to = val;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_FLUSH_TO, l2cap_add_conf_opt(&ptr, L2CAP_CONF_FLUSH_TO,
2, chan->flush_to); 2, chan->flush_to, endptr - ptr);
break; break;
case L2CAP_CONF_RFC: case L2CAP_CONF_RFC:
@ -3568,13 +3574,13 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
chan->fcs = 0; chan->fcs = 0;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
sizeof(rfc), (unsigned long) &rfc); sizeof(rfc), (unsigned long) &rfc, endptr - ptr);
break; break;
case L2CAP_CONF_EWS: case L2CAP_CONF_EWS:
chan->ack_win = min_t(u16, val, chan->ack_win); chan->ack_win = min_t(u16, val, chan->ack_win);
l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2, l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2,
chan->tx_win); chan->tx_win, endptr - ptr);
break; break;
case L2CAP_CONF_EFS: case L2CAP_CONF_EFS:
@ -3587,7 +3593,7 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len,
return -ECONNREFUSED; return -ECONNREFUSED;
l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs), l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs),
(unsigned long) &efs); (unsigned long) &efs, endptr - ptr);
break; break;
case L2CAP_CONF_FCS: case L2CAP_CONF_FCS:
@ -3692,7 +3698,7 @@ void __l2cap_connect_rsp_defer(struct l2cap_chan *chan)
return; return;
l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ, l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, buf), buf); l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
chan->num_conf_req++; chan->num_conf_req++;
} }
@ -3900,7 +3906,7 @@ sendresp:
u8 buf[128]; u8 buf[128];
set_bit(CONF_REQ_SENT, &chan->conf_state); set_bit(CONF_REQ_SENT, &chan->conf_state);
l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ, l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, buf), buf); l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
chan->num_conf_req++; chan->num_conf_req++;
} }
@ -3978,7 +3984,7 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
break; break;
l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ, l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, req), req); l2cap_build_conf_req(chan, req, sizeof(req)), req);
chan->num_conf_req++; chan->num_conf_req++;
break; break;
@ -4090,7 +4096,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
} }
/* Complete config. */ /* Complete config. */
len = l2cap_parse_conf_req(chan, rsp); len = l2cap_parse_conf_req(chan, rsp, sizeof(rsp));
if (len < 0) { if (len < 0) {
l2cap_send_disconn_req(chan, ECONNRESET); l2cap_send_disconn_req(chan, ECONNRESET);
goto unlock; goto unlock;
@ -4124,7 +4130,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
if (!test_and_set_bit(CONF_REQ_SENT, &chan->conf_state)) { if (!test_and_set_bit(CONF_REQ_SENT, &chan->conf_state)) {
u8 buf[64]; u8 buf[64];
l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ, l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, buf), buf); l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
chan->num_conf_req++; chan->num_conf_req++;
} }
@ -4184,7 +4190,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
char buf[64]; char buf[64];
len = l2cap_parse_conf_rsp(chan, rsp->data, len, len = l2cap_parse_conf_rsp(chan, rsp->data, len,
buf, &result); buf, sizeof(buf), &result);
if (len < 0) { if (len < 0) {
l2cap_send_disconn_req(chan, ECONNRESET); l2cap_send_disconn_req(chan, ECONNRESET);
goto done; goto done;
@ -4214,7 +4220,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
/* throw out any old stored conf requests */ /* throw out any old stored conf requests */
result = L2CAP_CONF_SUCCESS; result = L2CAP_CONF_SUCCESS;
len = l2cap_parse_conf_rsp(chan, rsp->data, len, len = l2cap_parse_conf_rsp(chan, rsp->data, len,
req, &result); req, sizeof(req), &result);
if (len < 0) { if (len < 0) {
l2cap_send_disconn_req(chan, ECONNRESET); l2cap_send_disconn_req(chan, ECONNRESET);
goto done; goto done;
@ -4791,7 +4797,7 @@ static void l2cap_do_create(struct l2cap_chan *chan, int result,
set_bit(CONF_REQ_SENT, &chan->conf_state); set_bit(CONF_REQ_SENT, &chan->conf_state);
l2cap_send_cmd(chan->conn, l2cap_get_ident(chan->conn), l2cap_send_cmd(chan->conn, l2cap_get_ident(chan->conn),
L2CAP_CONF_REQ, L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, buf), buf); l2cap_build_conf_req(chan, buf, sizeof(buf)), buf);
chan->num_conf_req++; chan->num_conf_req++;
} }
} }
@ -7465,7 +7471,7 @@ static void l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt)
set_bit(CONF_REQ_SENT, &chan->conf_state); set_bit(CONF_REQ_SENT, &chan->conf_state);
l2cap_send_cmd(conn, l2cap_get_ident(conn), l2cap_send_cmd(conn, l2cap_get_ident(conn),
L2CAP_CONF_REQ, L2CAP_CONF_REQ,
l2cap_build_conf_req(chan, buf), l2cap_build_conf_req(chan, buf, sizeof(buf)),
buf); buf);
chan->num_conf_req++; chan->num_conf_req++;
} }