(Please keep me in the CC list, I'm not subscribed to lkml) [1] L2CAP module dereferences an uninitialized pointer within l2cap_connect_req. [2] I'm currently testing a 2.6.35 kernel on a Nexus One with backported patches from bluetooth-2.6. When testing against certain BT devices, I'm seeing a null-pointer deref. The crash is caused by this portion of commit e9aeb2dd: @@ -2966,6 +2991,15 @@ sendresp: L2CAP_INFO_REQ, sizeof(info), &info); } + if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_REQ_SENT) && + result == L2CAP_CR_SUCCESS) { + u8 buf[128]; + l2cap_pi(sk)->conf_state |= L2CAP_CONF_REQ_SENT; + l2cap_send_cmd(conn, l2cap_get_ident(conn), L2CAP_CONF_REQ, + l2cap_build_conf_req(sk, buf), buf); + l2cap_pi(sk)->num_conf_req++; + } + return 0; } Multiple error cases jump to the response & sendresp labels prior to initializing the "sk" variable. In the case I'm currently seeing, the remote BT device fails to properly secure the ACL, making this crash 100% reproducible. [3] Bluetooth, L2CAP [4] This bug appears to be in the mainline 2.6.36-rc? kernel, in addition to multiple Bluetooth development trees The following patch fixes the crash. --nathan --- In error cases when the ACL is insecure or we fail to allocate a new struct sock, we jump to the "response" label. If so, "sk" will be uninitialized and the kernel crashes. Signed-off-by: Nathan Holstein <nathan.holstein@xxxxxxxxx> --- net/bluetooth/l2cap.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c index d527b10..10ae0af 100644 --- a/net/bluetooth/l2cap.c +++ b/net/bluetooth/l2cap.c @@ -2911,7 +2911,7 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd struct l2cap_chan_list *list = &conn->chan_list; struct l2cap_conn_req *req = (struct l2cap_conn_req *) data; struct l2cap_conn_rsp rsp; - struct sock *parent, *uninitialized_var(sk); + struct sock *parent, *sk = 0; int result, status = L2CAP_CS_NO_INFO; u16 dcid = 0, scid = __le16_to_cpu(req->scid); @@ -3020,7 +3020,7 @@ sendresp: L2CAP_INFO_REQ, sizeof(info), &info); } - if (!(l2cap_pi(sk)->conf_state & L2CAP_CONF_REQ_SENT) && + if (sk && !(l2cap_pi(sk)->conf_state & L2CAP_CONF_REQ_SENT) && result == L2CAP_CR_SUCCESS) { u8 buf[128]; l2cap_pi(sk)->conf_state |= L2CAP_CONF_REQ_SENT; -- 1.7.2.3 -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html