From 8ff52f7d04d9cc31f1e81dcf9a2ba6335ed34905 Mon Sep 17 00:00:00 2001 From: Dean Jenkins Date: Thu, 28 Feb 2013 14:21:55 +0000 Subject: [PATCH] Bluetooth: Return RFCOMM session ptrs to avoid freed session 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 Acked-by: Marcel Holtmann Signed-off-by: Gustavo Padovan --- 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 e2e3ecad1008..a4e38ead2282 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 d9e97cf1792b..2b5c543638ba 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); } -- 2.30.2