As the comment for l2cap_get_chan_by_scid indicated, the function used
to return a locked socket. The lock for the socket was acquired while
the channel list was also locked.
When locking was moved over to the l2cap_chan structure, the channel
lock was no longer acquired with the channel list still locked. This
made it possible for the l2cap_chan to be deleted after
conn->chan_lock was released but before l2cap_chan_lock was called.
Making the call to l2cap_chan_lock before releasing conn->chan_lock
makes it impossible for the l2cap_chan to be deleted at the wrong
time.
Signed-off-by: Mat Martineau <mathewm@xxxxxxxxxxxxxx>
---
net/bluetooth/l2cap_core.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 5d556b0..813cf06 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -98,13 +98,15 @@ static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn, u16
}
/* Find channel with given SCID.
- * Returns locked socket */
+ * Returns locked channel. */
static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn, u16 cid)
{
struct l2cap_chan *c;
mutex_lock(&conn->chan_lock);
c = __l2cap_get_chan_by_scid(conn, cid);
+ if (c)
+ l2cap_chan_lock(c);
mutex_unlock(&conn->chan_lock);
return c;
@@ -3141,8 +3143,6 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
if (!chan)
return -ENOENT;
- l2cap_chan_lock(chan);
-
if (chan->state != BT_CONFIG && chan->state != BT_CONNECT2) {
struct l2cap_cmd_rej_cid rej;
@@ -3255,8 +3255,6 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
if (!chan)
return 0;
- l2cap_chan_lock(chan);
-
switch (result) {
case L2CAP_CONF_SUCCESS:
l2cap_conf_rfc_get(chan, rsp->data, len);
@@ -4589,8 +4587,6 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
return 0;
}
- l2cap_chan_lock(chan);
-
BT_DBG("chan %p, len %d", chan, skb->len);
if (chan->state != BT_CONNECTED)
--
1.7.10
--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
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