From: Dean Jenkins <Dean_Jenkins@xxxxxxxxxx>
Unfortunately, the design retains local copies of the s RFCOMM
session pointer in various code blocks and this invites the erroneous
access to a freed RFCOMM session structure.
Therefore, return the RFCOMM session pointer back up the call stack
to avoid accessing a freed RFCOMM session structure. When the RFCOMM
session is deleted, NULL is passed up the call stack.
If active DLCs exist when the rfcomm session is terminating,
avoid a memory leak of rfcomm_dlc structures by ensuring that
rfcomm_session_close() is used instead of rfcomm_session_del().
Signed-off-by: Dean Jenkins <Dean_Jenkins@xxxxxxxxxx>
---
include/net/bluetooth/rfcomm.h | 3 +-
net/bluetooth/rfcomm/core.c | 106 +++++++++++++++++++++-------------------
2 files changed, 58 insertions(+), 51 deletions(-)
diff --git a/include/net/bluetooth/rfcomm.h b/include/net/bluetooth/rfcomm.h
index e2e3eca..a4e38ea 100644
--- a/include/net/bluetooth/rfcomm.h
+++ b/include/net/bluetooth/rfcomm.h
@@ -278,7 +278,8 @@ void rfcomm_session_getaddr(struct rfcomm_session *s, bdaddr_t *src,
static inline void rfcomm_session_hold(struct rfcomm_session *s)
{
- atomic_inc(&s->refcnt);
+ if (s)
+ atomic_inc(&s->refcnt);
}
/* ---- RFCOMM sockets ---- */
diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index af0c26d..60d2f1a 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -69,7 +69,7 @@ static struct rfcomm_session *rfcomm_session_create(bdaddr_t *src,
u8 sec_level,
int *err);
static struct rfcomm_session *rfcomm_session_get(bdaddr_t *src, bdaddr_t *dst);
-static void rfcomm_session_del(struct rfcomm_session *s);
+static struct rfcomm_session *rfcomm_session_del(struct rfcomm_session *s);
/* ---- RFCOMM frame parsing macros ---- */
#define __get_dlci(b) ((b & 0xfc) >> 2)
@@ -108,10 +108,12 @@ static void rfcomm_schedule(void)
wake_up_process(rfcomm_thread);
}
-static void rfcomm_session_put(struct rfcomm_session *s)
+static struct rfcomm_session *rfcomm_session_put(struct rfcomm_session *s)
{
- if (atomic_dec_and_test(&s->refcnt))
- rfcomm_session_del(s);
+ if (s && atomic_dec_and_test(&s->refcnt))
+ s = rfcomm_session_del(s);
+
+ return s;
}
/* ---- RFCOMM FCS computation ---- */
@@ -631,7 +633,7 @@ static struct rfcomm_session *rfcomm_session_add(struct socket *sock, int state)
return s;
}
-static void rfcomm_session_del(struct rfcomm_session *s)
+static struct rfcomm_session *rfcomm_session_del(struct rfcomm_session *s)
{
int state = s->state;
@@ -648,6 +650,8 @@ static void rfcomm_session_del(struct rfcomm_session *s)
if (state != BT_LISTEN)
module_put(THIS_MODULE);
+
+ return NULL;
}
static struct rfcomm_session *rfcomm_session_get(bdaddr_t *src, bdaddr_t *dst)
@@ -666,7 +670,8 @@ static struct rfcomm_session *rfcomm_session_get(bdaddr_t *src, bdaddr_t *dst)
return NULL;
}
-static void rfcomm_session_close(struct rfcomm_session *s, int err)
+static struct rfcomm_session *rfcomm_session_close(struct rfcomm_session *s,
+ int err)
{
struct rfcomm_dlc *d;
struct list_head *p, *n;
@@ -685,7 +690,7 @@ static void rfcomm_session_close(struct rfcomm_session *s, int err)
}
rfcomm_session_clear_timer(s);
- rfcomm_session_put(s);
+ return rfcomm_session_put(s);
}
static struct rfcomm_session *rfcomm_session_create(bdaddr_t *src,
@@ -737,8 +742,7 @@ static struct rfcomm_session *rfcomm_session_create(bdaddr_t *src,
if (*err == 0 || *err == -EINPROGRESS)
return s;
- rfcomm_session_del(s);
- return NULL;
+ return rfcomm_session_del(s);
failed:
sock_release(sock);
@@ -1127,7 +1131,7 @@ static void rfcomm_make_uih(struct sk_buff *skb, u8 addr)
}
/* ---- RFCOMM frame reception ---- */
-static int rfcomm_recv_ua(struct rfcomm_session *s, u8 dlci)
+static struct rfcomm_session *rfcomm_recv_ua(struct rfcomm_session *s, u8 dlci)
{
BT_DBG("session %p state %ld dlci %d", s, s->state, dlci);
@@ -1136,7 +1140,7 @@ static int rfcomm_recv_ua(struct rfcomm_session *s, u8 dlci)
struct rfcomm_dlc *d = rfcomm_dlc_get(s, dlci);
if (!d) {
rfcomm_send_dm(s, dlci);
- return 0;
+ return s;
}
switch (d->state) {
@@ -1172,25 +1176,14 @@ static int rfcomm_recv_ua(struct rfcomm_session *s, u8 dlci)
break;
case BT_DISCONN:
- /* rfcomm_session_put is called later so don't do
- * anything here otherwise we will mess up the session
- * reference counter:
- *
- * (a) when we are the initiator dlc_unlink will drive
- * the reference counter to 0 (there is no initial put
- * after session_add)
- *
- * (b) when we are not the initiator rfcomm_rx_process
- * will explicitly call put to balance the initial hold
- * done after session add.
- */
+ s = rfcomm_session_close(s, ECONNRESET);
break;
}
}
- return 0;
+ return s;
}
-static int rfcomm_recv_dm(struct rfcomm_session *s, u8 dlci)
+static struct rfcomm_session *rfcomm_recv_dm(struct rfcomm_session *s, u8 dlci)
{
int err = 0;
@@ -1215,12 +1208,13 @@ static int rfcomm_recv_dm(struct rfcomm_session *s, u8 dlci)
err = ECONNRESET;
s->state = BT_CLOSED;
- rfcomm_session_close(s, err);
+ s = rfcomm_session_close(s, err);
}
- return 0;
+ return s;
}
-static int rfcomm_recv_disc(struct rfcomm_session *s, u8 dlci)
+static struct rfcomm_session *rfcomm_recv_disc(struct rfcomm_session *s,
+ u8 dlci)
{
int err = 0;
@@ -1250,10 +1244,9 @@ static int rfcomm_recv_disc(struct rfcomm_session *s, u8 dlci)
err = ECONNRESET;
s->state = BT_CLOSED;
- rfcomm_session_close(s, err);
+ s = rfcomm_session_close(s, err);
}
-
- return 0;
+ return s;
}
void rfcomm_dlc_accept(struct rfcomm_dlc *d)
@@ -1674,11 +1667,18 @@ drop:
return 0;
}
-static int rfcomm_recv_frame(struct rfcomm_session *s, struct sk_buff *skb)
+static struct rfcomm_session *rfcomm_recv_frame(struct rfcomm_session *s,
+ struct sk_buff *skb)
{
struct rfcomm_hdr *hdr = (void *) skb->data;
u8 type, dlci, fcs;
+ if (!s) {
+ /* no session, so free socket data */
+ kfree_skb(skb);
+ return s;
+ }
+
dlci = __get_dlci(hdr->addr);
type = __get_type(hdr->ctrl);
@@ -1689,7 +1689,7 @@ static int rfcomm_recv_frame(struct rfcomm_session *s, struct sk_buff *skb)
if (__check_fcs(skb->data, type, fcs)) {
BT_ERR("bad checksum in packet");
kfree_skb(skb);
- return -EILSEQ;
+ return s;
}
if (__test_ea(hdr->len))
@@ -1705,22 +1705,23 @@ static int rfcomm_recv_frame(struct rfcomm_session *s, struct sk_buff *skb)
case RFCOMM_DISC:
if (__test_pf(hdr->ctrl))
- rfcomm_recv_disc(s, dlci);
+ s = rfcomm_recv_disc(s, dlci);
break;
case RFCOMM_UA:
if (__test_pf(hdr->ctrl))
- rfcomm_recv_ua(s, dlci);
+ s = rfcomm_recv_ua(s, dlci);
break;
case RFCOMM_DM:
- rfcomm_recv_dm(s, dlci);
+ s = rfcomm_recv_dm(s, dlci);
break;
case RFCOMM_UIH:
- if (dlci)
- return rfcomm_recv_data(s, dlci, __test_pf(hdr->ctrl), skb);
-
+ if (dlci) {
+ rfcomm_recv_data(s, dlci, __test_pf(hdr->ctrl), skb);
+ return s;
+ }
rfcomm_recv_mcc(s, skb);
break;
@@ -1729,7 +1730,7 @@ static int rfcomm_recv_frame(struct rfcomm_session *s, struct sk_buff *skb)
break;
}
kfree_skb(skb);
- return 0;
+ return s;
}
/* ---- Connection and data processing ---- */
@@ -1866,7 +1867,7 @@ static void rfcomm_process_dlcs(struct rfcomm_session *s)
}
}
-static void rfcomm_process_rx(struct rfcomm_session *s)
+static struct rfcomm_session *rfcomm_process_rx(struct rfcomm_session *s)
{
struct socket *sock = s->sock;
struct sock *sk = sock->sk;
@@ -1878,17 +1879,20 @@ static void rfcomm_process_rx(struct rfcomm_session *s)
while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
skb_orphan(skb);
if (!skb_linearize(skb))
- rfcomm_recv_frame(s, skb);
+ s = rfcomm_recv_frame(s, skb);
else
kfree_skb(skb);
}
- if (sk->sk_state == BT_CLOSED) {
+ if (s && (sk->sk_state == BT_CLOSED)) {
if (!s->initiator)
- rfcomm_session_put(s);
+ s = rfcomm_session_put(s);
- rfcomm_session_close(s, sk->sk_err);
+ if (s)
+ s = rfcomm_session_close(s, sk->sk_err);
}
+
+ return s;
}
static void rfcomm_accept_connection(struct rfcomm_session *s)
@@ -1925,7 +1929,7 @@ static void rfcomm_accept_connection(struct rfcomm_session *s)
sock_release(nsock);
}
-static void rfcomm_check_connection(struct rfcomm_session *s)
+static struct rfcomm_session *rfcomm_check_connection(struct rfcomm_session *s)
{
struct sock *sk = s->sock->sk;
@@ -1944,9 +1948,10 @@ static void rfcomm_check_connection(struct rfcomm_session *s)
case BT_CLOSED:
s->state = BT_CLOSED;
- rfcomm_session_close(s, sk->sk_err);
+ s = rfcomm_session_close(s, sk->sk_err);
break;
}
+ return s;
}
static void rfcomm_process_sessions(void)
@@ -1975,15 +1980,16 @@ static void rfcomm_process_sessions(void)
switch (s->state) {
case BT_BOUND:
- rfcomm_check_connection(s);
+ s = rfcomm_check_connection(s);
break;
default:
- rfcomm_process_rx(s);
+ s = rfcomm_process_rx(s);
break;
}
- rfcomm_process_dlcs(s);
+ if (s)
+ rfcomm_process_dlcs(s);
rfcomm_session_put(s);
}
--
1.7.10.1
--
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