From f4777569204cb59f2f04fbe9ef4e9a6918209104 Mon Sep 17 00:00:00 2001 From: Marcel Holtmann Date: Mon, 8 Jan 2007 02:16:23 +0100 Subject: [PATCH] [Bluetooth] Add packet size checks for CAPI messages With malformed packets it might be possible to overwrite internal CMTP and CAPI data structures. This patch adds additional length checks to prevent these kinds of remote attacks. Signed-off-by: Marcel Holtmann --- net/bluetooth/cmtp/capi.c | 39 +++++++++++++++++++++++++++++++++------ 1 file changed, 33 insertions(+), 6 deletions(-) diff --git a/net/bluetooth/cmtp/capi.c b/net/bluetooth/cmtp/capi.c index be04e9fb11..ab166b48ce 100644 --- a/net/bluetooth/cmtp/capi.c +++ b/net/bluetooth/cmtp/capi.c @@ -196,6 +196,9 @@ static void cmtp_recv_interopmsg(struct cmtp_session *session, struct sk_buff *s switch (CAPIMSG_SUBCOMMAND(skb->data)) { case CAPI_CONF: + if (skb->len < CAPI_MSG_BASELEN + 10) + break; + func = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 5); info = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 8); @@ -226,6 +229,9 @@ static void cmtp_recv_interopmsg(struct cmtp_session *session, struct sk_buff *s break; case CAPI_FUNCTION_GET_PROFILE: + if (skb->len < CAPI_MSG_BASELEN + 11 + sizeof(capi_profile)) + break; + controller = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 11); msgnum = CAPIMSG_MSGID(skb->data); @@ -246,17 +252,26 @@ static void cmtp_recv_interopmsg(struct cmtp_session *session, struct sk_buff *s break; case CAPI_FUNCTION_GET_MANUFACTURER: + if (skb->len < CAPI_MSG_BASELEN + 15) + break; + controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 10); if (!info && ctrl) { + int len = min_t(uint, CAPI_MANUFACTURER_LEN, + skb->data[CAPI_MSG_BASELEN + 14]); + + memset(ctrl->manu, 0, CAPI_MANUFACTURER_LEN); strncpy(ctrl->manu, - skb->data + CAPI_MSG_BASELEN + 15, - skb->data[CAPI_MSG_BASELEN + 14]); + skb->data + CAPI_MSG_BASELEN + 15, len); } break; case CAPI_FUNCTION_GET_VERSION: + if (skb->len < CAPI_MSG_BASELEN + 32) + break; + controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 12); if (!info && ctrl) { @@ -269,13 +284,18 @@ static void cmtp_recv_interopmsg(struct cmtp_session *session, struct sk_buff *s break; case CAPI_FUNCTION_GET_SERIAL_NUMBER: + if (skb->len < CAPI_MSG_BASELEN + 17) + break; + controller = CAPIMSG_U32(skb->data, CAPI_MSG_BASELEN + 12); if (!info && ctrl) { + int len = min_t(uint, CAPI_SERIAL_LEN, + skb->data[CAPI_MSG_BASELEN + 16]); + memset(ctrl->serial, 0, CAPI_SERIAL_LEN); strncpy(ctrl->serial, - skb->data + CAPI_MSG_BASELEN + 17, - skb->data[CAPI_MSG_BASELEN + 16]); + skb->data + CAPI_MSG_BASELEN + 17, len); } break; @@ -284,14 +304,18 @@ static void cmtp_recv_interopmsg(struct cmtp_session *session, struct sk_buff *s break; case CAPI_IND: + if (skb->len < CAPI_MSG_BASELEN + 6) + break; + func = CAPIMSG_U16(skb->data, CAPI_MSG_BASELEN + 3); if (func == CAPI_FUNCTION_LOOPBACK) { + int len = min_t(uint, skb->len - CAPI_MSG_BASELEN - 6, + skb->data[CAPI_MSG_BASELEN + 5]); appl = CAPIMSG_APPID(skb->data); msgnum = CAPIMSG_MSGID(skb->data); cmtp_send_interopmsg(session, CAPI_RESP, appl, msgnum, func, - skb->data + CAPI_MSG_BASELEN + 6, - skb->data[CAPI_MSG_BASELEN + 5]); + skb->data + CAPI_MSG_BASELEN + 6, len); } break; @@ -309,6 +333,9 @@ void cmtp_recv_capimsg(struct cmtp_session *session, struct sk_buff *skb) BT_DBG("session %p skb %p len %d", session, skb, skb->len); + if (skb->len < CAPI_MSG_BASELEN) + return; + if (CAPIMSG_COMMAND(skb->data) == CAPI_INTEROPERABILITY) { cmtp_recv_interopmsg(session, skb); return; -- 2.39.5