linux/net/llc/llc_s_ac.c
Eric Biggers c6ee11c39f llc: fix sk_buff leak in llc_sap_state_process()
syzbot reported:

    BUG: memory leak
    unreferenced object 0xffff888116270800 (size 224):
       comm "syz-executor641", pid 7047, jiffies 4294947360 (age 13.860s)
       hex dump (first 32 bytes):
         00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
         00 20 e1 2a 81 88 ff ff 00 40 3d 2a 81 88 ff ff  . .*.....@=*....
       backtrace:
         [<000000004d41b4cc>] kmemleak_alloc_recursive  include/linux/kmemleak.h:55 [inline]
         [<000000004d41b4cc>] slab_post_alloc_hook mm/slab.h:439 [inline]
         [<000000004d41b4cc>] slab_alloc_node mm/slab.c:3269 [inline]
         [<000000004d41b4cc>] kmem_cache_alloc_node+0x153/0x2a0 mm/slab.c:3579
         [<00000000506a5965>] __alloc_skb+0x6e/0x210 net/core/skbuff.c:198
         [<000000001ba5a161>] alloc_skb include/linux/skbuff.h:1058 [inline]
         [<000000001ba5a161>] alloc_skb_with_frags+0x5f/0x250  net/core/skbuff.c:5327
         [<0000000047d9c78b>] sock_alloc_send_pskb+0x269/0x2a0  net/core/sock.c:2225
         [<000000003828fe54>] sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2242
         [<00000000e34d94f9>] llc_ui_sendmsg+0x10a/0x540 net/llc/af_llc.c:933
         [<00000000de2de3fb>] sock_sendmsg_nosec net/socket.c:652 [inline]
         [<00000000de2de3fb>] sock_sendmsg+0x54/0x70 net/socket.c:671
         [<000000008fe16e7a>] __sys_sendto+0x148/0x1f0 net/socket.c:1964
	 [...]

The bug is that llc_sap_state_process() always takes an extra reference
to the skb, but sometimes neither llc_sap_next_state() nor
llc_sap_state_process() itself drops this reference.

Fix it by changing llc_sap_next_state() to never consume a reference to
the skb, rather than sometimes do so and sometimes not.  Then remove the
extra skb_get() and kfree_skb() from llc_sap_state_process().

Reported-by: syzbot+6bf095f9becf5efef645@syzkaller.appspotmail.com
Reported-by: syzbot+31c16aa4202dace3812e@syzkaller.appspotmail.com
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
2019-10-08 13:23:05 -07:00

215 lines
5.9 KiB
C

/*
* llc_s_ac.c - actions performed during sap state transition.
*
* Description :
* Functions in this module are implementation of sap component actions.
* Details of actions can be found in IEEE-802.2 standard document.
* All functions have one sap and one event as input argument. All of
* them return 0 On success and 1 otherwise.
*
* Copyright (c) 1997 by Procom Technology, Inc.
* 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* This program can be redistributed or modified under the terms of the
* GNU General Public License as published by the Free Software Foundation.
* This program is distributed without any warranty or implied warranty
* of merchantability or fitness for a particular purpose.
*
* See the GNU General Public License for more details.
*/
#include <linux/netdevice.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/llc_s_ac.h>
#include <net/llc_s_ev.h>
#include <net/llc_sap.h>
/**
* llc_sap_action_unit_data_ind - forward UI PDU to network layer
* @sap: SAP
* @skb: the event to forward
*
* Received a UI PDU from MAC layer; forward to network layer as a
* UNITDATA INDICATION; verify our event is the kind we expect
*/
int llc_sap_action_unitdata_ind(struct llc_sap *sap, struct sk_buff *skb)
{
llc_sap_rtn_pdu(sap, skb);
return 0;
}
/**
* llc_sap_action_send_ui - sends UI PDU resp to UNITDATA REQ to MAC layer
* @sap: SAP
* @skb: the event to send
*
* Sends a UI PDU to the MAC layer in response to a UNITDATA REQUEST
* primitive from the network layer. Verifies event is a primitive type of
* event. Verify the primitive is a UNITDATA REQUEST.
*/
int llc_sap_action_send_ui(struct llc_sap *sap, struct sk_buff *skb)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
int rc;
llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap,
ev->daddr.lsap, LLC_PDU_CMD);
llc_pdu_init_as_ui_cmd(skb);
rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac);
if (likely(!rc)) {
skb_get(skb);
rc = dev_queue_xmit(skb);
}
return rc;
}
/**
* llc_sap_action_send_xid_c - send XID PDU as response to XID REQ
* @sap: SAP
* @skb: the event to send
*
* Send a XID command PDU to MAC layer in response to a XID REQUEST
* primitive from the network layer. Verify event is a primitive type
* event. Verify the primitive is a XID REQUEST.
*/
int llc_sap_action_send_xid_c(struct llc_sap *sap, struct sk_buff *skb)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
int rc;
llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap,
ev->daddr.lsap, LLC_PDU_CMD);
llc_pdu_init_as_xid_cmd(skb, LLC_XID_NULL_CLASS_2, 0);
rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac);
if (likely(!rc)) {
skb_get(skb);
rc = dev_queue_xmit(skb);
}
return rc;
}
/**
* llc_sap_action_send_xid_r - send XID PDU resp to MAC for received XID
* @sap: SAP
* @skb: the event to send
*
* Send XID response PDU to MAC in response to an earlier received XID
* command PDU. Verify event is a PDU type event
*/
int llc_sap_action_send_xid_r(struct llc_sap *sap, struct sk_buff *skb)
{
u8 mac_da[ETH_ALEN], mac_sa[ETH_ALEN], dsap;
int rc = 1;
struct sk_buff *nskb;
llc_pdu_decode_sa(skb, mac_da);
llc_pdu_decode_da(skb, mac_sa);
llc_pdu_decode_ssap(skb, &dsap);
nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
sizeof(struct llc_xid_info));
if (!nskb)
goto out;
llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap, dsap,
LLC_PDU_RSP);
llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 0);
rc = llc_mac_hdr_init(nskb, mac_sa, mac_da);
if (likely(!rc))
rc = dev_queue_xmit(nskb);
out:
return rc;
}
/**
* llc_sap_action_send_test_c - send TEST PDU to MAC in resp to TEST REQ
* @sap: SAP
* @skb: the event to send
*
* Send a TEST command PDU to the MAC layer in response to a TEST REQUEST
* primitive from the network layer. Verify event is a primitive type
* event; verify the primitive is a TEST REQUEST.
*/
int llc_sap_action_send_test_c(struct llc_sap *sap, struct sk_buff *skb)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
int rc;
llc_pdu_header_init(skb, LLC_PDU_TYPE_U, ev->saddr.lsap,
ev->daddr.lsap, LLC_PDU_CMD);
llc_pdu_init_as_test_cmd(skb);
rc = llc_mac_hdr_init(skb, ev->saddr.mac, ev->daddr.mac);
if (likely(!rc)) {
skb_get(skb);
rc = dev_queue_xmit(skb);
}
return rc;
}
int llc_sap_action_send_test_r(struct llc_sap *sap, struct sk_buff *skb)
{
u8 mac_da[ETH_ALEN], mac_sa[ETH_ALEN], dsap;
struct sk_buff *nskb;
int rc = 1;
u32 data_size;
llc_pdu_decode_sa(skb, mac_da);
llc_pdu_decode_da(skb, mac_sa);
llc_pdu_decode_ssap(skb, &dsap);
/* The test request command is type U (llc_len = 3) */
data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
if (!nskb)
goto out;
llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap, dsap,
LLC_PDU_RSP);
llc_pdu_init_as_test_rsp(nskb, skb);
rc = llc_mac_hdr_init(nskb, mac_sa, mac_da);
if (likely(!rc))
rc = dev_queue_xmit(nskb);
out:
return rc;
}
/**
* llc_sap_action_report_status - report data link status to layer mgmt
* @sap: SAP
* @skb: the event to send
*
* Report data link status to layer management. Verify our event is the
* kind we expect.
*/
int llc_sap_action_report_status(struct llc_sap *sap, struct sk_buff *skb)
{
return 0;
}
/**
* llc_sap_action_xid_ind - send XID PDU resp to net layer via XID IND
* @sap: SAP
* @skb: the event to send
*
* Send a XID response PDU to the network layer via a XID INDICATION
* primitive.
*/
int llc_sap_action_xid_ind(struct llc_sap *sap, struct sk_buff *skb)
{
llc_sap_rtn_pdu(sap, skb);
return 0;
}
/**
* llc_sap_action_test_ind - send TEST PDU to net layer via TEST IND
* @sap: SAP
* @skb: the event to send
*
* Send a TEST response PDU to the network layer via a TEST INDICATION
* primitive. Verify our event is a PDU type event.
*/
int llc_sap_action_test_ind(struct llc_sap *sap, struct sk_buff *skb)
{
llc_sap_rtn_pdu(sap, skb);
return 0;
}