linux/net/x25/x25_dev.c
Eric Dumazet 8265792bf8 net: silence KCSAN warnings around sk_add_backlog() calls
sk_add_backlog() callers usually read sk->sk_rcvbuf without
owning the socket lock. This means sk_rcvbuf value can
be changed by other cpus, and KCSAN complains.

Add READ_ONCE() annotations to document the lockless nature
of these reads.

Note that writes over sk_rcvbuf should also use WRITE_ONCE(),
but this will be done in separate patches to ease stable
backports (if we decide this is relevant for stable trees).

BUG: KCSAN: data-race in tcp_add_backlog / tcp_recvmsg

write to 0xffff88812ab369f8 of 8 bytes by interrupt on cpu 1:
 __sk_add_backlog include/net/sock.h:902 [inline]
 sk_add_backlog include/net/sock.h:933 [inline]
 tcp_add_backlog+0x45a/0xcc0 net/ipv4/tcp_ipv4.c:1737
 tcp_v4_rcv+0x1aba/0x1bf0 net/ipv4/tcp_ipv4.c:1925
 ip_protocol_deliver_rcu+0x51/0x470 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x110/0x140 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x133/0x210 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x121/0x160 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x18f/0x1a0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0xa7/0xe0 net/core/dev.c:5004
 __netif_receive_skb+0x37/0xf0 net/core/dev.c:5118
 netif_receive_skb_internal+0x59/0x190 net/core/dev.c:5208
 napi_skb_finish net/core/dev.c:5671 [inline]
 napi_gro_receive+0x28f/0x330 net/core/dev.c:5704
 receive_buf+0x284/0x30b0 drivers/net/virtio_net.c:1061
 virtnet_receive drivers/net/virtio_net.c:1323 [inline]
 virtnet_poll+0x436/0x7d0 drivers/net/virtio_net.c:1428
 napi_poll net/core/dev.c:6352 [inline]
 net_rx_action+0x3ae/0xa50 net/core/dev.c:6418

read to 0xffff88812ab369f8 of 8 bytes by task 7271 on cpu 0:
 tcp_recvmsg+0x470/0x1a30 net/ipv4/tcp.c:2047
 inet_recvmsg+0xbb/0x250 net/ipv4/af_inet.c:838
 sock_recvmsg_nosec net/socket.c:871 [inline]
 sock_recvmsg net/socket.c:889 [inline]
 sock_recvmsg+0x92/0xb0 net/socket.c:885
 sock_read_iter+0x15f/0x1e0 net/socket.c:967
 call_read_iter include/linux/fs.h:1864 [inline]
 new_sync_read+0x389/0x4f0 fs/read_write.c:414
 __vfs_read+0xb1/0xc0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7271 Comm: syz-fuzzer Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
2019-10-09 21:42:59 -07:00

228 lines
4.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* X.25 Packet Layer release 002
*
* This is ALPHA test software. This code may break your machine, randomly fail to work with new
* releases, misbehave and/or generally screw up. It might even work.
*
* This code REQUIRES 2.1.15 or higher
*
* History
* X.25 001 Jonathan Naylor Started coding.
* 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
*/
#define pr_fmt(fmt) "X25: " fmt
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/if_arp.h>
#include <net/x25.h>
#include <net/x25device.h>
static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
{
struct sock *sk;
unsigned short frametype;
unsigned int lci;
if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
return 0;
frametype = skb->data[2];
lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
/*
* LCI of zero is always for us, and its always a link control
* frame.
*/
if (lci == 0) {
x25_link_control(skb, nb, frametype);
return 0;
}
/*
* Find an existing socket.
*/
if ((sk = x25_find_socket(lci, nb)) != NULL) {
int queued = 1;
skb_reset_transport_header(skb);
bh_lock_sock(sk);
if (!sock_owned_by_user(sk)) {
queued = x25_process_rx_frame(sk, skb);
} else {
queued = !sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
}
bh_unlock_sock(sk);
sock_put(sk);
return queued;
}
/*
* Is is a Call Request ? if so process it.
*/
if (frametype == X25_CALL_REQUEST)
return x25_rx_call_request(skb, nb, lci);
/*
* Its not a Call Request, nor is it a control frame.
* Can we forward it?
*/
if (x25_forward_data(lci, nb, skb)) {
if (frametype == X25_CLEAR_CONFIRMATION) {
x25_clear_forward_by_lci(lci);
}
kfree_skb(skb);
return 1;
}
/*
x25_transmit_clear_request(nb, lci, 0x0D);
*/
if (frametype != X25_CLEAR_CONFIRMATION)
pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
return 0;
}
int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
struct packet_type *ptype, struct net_device *orig_dev)
{
struct sk_buff *nskb;
struct x25_neigh *nb;
if (!net_eq(dev_net(dev), &init_net))
goto drop;
nskb = skb_copy(skb, GFP_ATOMIC);
if (!nskb)
goto drop;
kfree_skb(skb);
skb = nskb;
/*
* Packet received from unrecognised device, throw it away.
*/
nb = x25_get_neigh(dev);
if (!nb) {
pr_debug("unknown neighbour - %s\n", dev->name);
goto drop;
}
if (!pskb_may_pull(skb, 1))
return 0;
switch (skb->data[0]) {
case X25_IFACE_DATA:
skb_pull(skb, 1);
if (x25_receive_data(skb, nb)) {
x25_neigh_put(nb);
goto out;
}
break;
case X25_IFACE_CONNECT:
x25_link_established(nb);
break;
case X25_IFACE_DISCONNECT:
x25_link_terminated(nb);
break;
}
x25_neigh_put(nb);
drop:
kfree_skb(skb);
out:
return 0;
}
void x25_establish_link(struct x25_neigh *nb)
{
struct sk_buff *skb;
unsigned char *ptr;
switch (nb->dev->type) {
case ARPHRD_X25:
if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
pr_err("x25_dev: out of memory\n");
return;
}
ptr = skb_put(skb, 1);
*ptr = X25_IFACE_CONNECT;
break;
#if IS_ENABLED(CONFIG_LLC)
case ARPHRD_ETHER:
return;
#endif
default:
return;
}
skb->protocol = htons(ETH_P_X25);
skb->dev = nb->dev;
dev_queue_xmit(skb);
}
void x25_terminate_link(struct x25_neigh *nb)
{
struct sk_buff *skb;
unsigned char *ptr;
#if IS_ENABLED(CONFIG_LLC)
if (nb->dev->type == ARPHRD_ETHER)
return;
#endif
if (nb->dev->type != ARPHRD_X25)
return;
skb = alloc_skb(1, GFP_ATOMIC);
if (!skb) {
pr_err("x25_dev: out of memory\n");
return;
}
ptr = skb_put(skb, 1);
*ptr = X25_IFACE_DISCONNECT;
skb->protocol = htons(ETH_P_X25);
skb->dev = nb->dev;
dev_queue_xmit(skb);
}
void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
{
unsigned char *dptr;
skb_reset_network_header(skb);
switch (nb->dev->type) {
case ARPHRD_X25:
dptr = skb_push(skb, 1);
*dptr = X25_IFACE_DATA;
break;
#if IS_ENABLED(CONFIG_LLC)
case ARPHRD_ETHER:
kfree_skb(skb);
return;
#endif
default:
kfree_skb(skb);
return;
}
skb->protocol = htons(ETH_P_X25);
skb->dev = nb->dev;
dev_queue_xmit(skb);
}