After commit
5271953cad31 ("rxrpc: Use the UDP encap_rcv hook"),
rxrpc_input_packet() is directly called from lockless UDP receive
path, under rcu_read_lock() protection.
It must therefore use RCU rules :
- udp_sk->sk_user_data can be cleared at any point in this function.
rcu_dereference_sk_user_data() is what we need here.
- Also, since sk_user_data might have been set in rxrpc_open_socket()
we must observe a proper RCU grace period before kfree(local) in
rxrpc_lookup_local()
v4: @local can be NULL in xrpc_lookup_local() as reported by kbuild test robot <lkp@intel.com>
and Julia Lawall <julia.lawall@lip6.fr>, thanks !
v3,v2 : addressed David Howells feedback, thanks !
syzbot reported :
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 19236 Comm: syz-executor703 Not tainted 5.1.0-rc6 #79
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__lock_acquire+0xbef/0x3fb0 kernel/locking/lockdep.c:3573
Code: 00 0f 85 a5 1f 00 00 48 81 c4 10 01 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 4a 21 00 00 49 81 7d 00 20 54 9c 89 0f 84 cf f4
RSP: 0018:
ffff88809d7aef58 EFLAGS:
00010002
RAX:
dffffc0000000000 RBX:
0000000000000000 RCX:
0000000000000000
RDX:
0000000000000026 RSI:
0000000000000000 RDI:
0000000000000001
RBP:
ffff88809d7af090 R08:
0000000000000001 R09:
0000000000000001
R10:
ffffed1015d05bc7 R11:
ffff888089428600 R12:
0000000000000000
R13:
0000000000000130 R14:
0000000000000001 R15:
0000000000000001
FS:
00007f059044d700(0000) GS:
ffff8880ae800000(0000) knlGS:
0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
CR2:
00000000004b6040 CR3:
00000000955ca000 CR4:
00000000001406f0
Call Trace:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:152
skb_queue_tail+0x26/0x150 net/core/skbuff.c:2972
rxrpc_reject_packet net/rxrpc/input.c:1126 [inline]
rxrpc_input_packet+0x4a0/0x5536 net/rxrpc/input.c:1414
udp_queue_rcv_one_skb+0xaf2/0x1780 net/ipv4/udp.c:2011
udp_queue_rcv_skb+0x128/0x730 net/ipv4/udp.c:2085
udp_unicast_rcv_skb.isra.0+0xb9/0x360 net/ipv4/udp.c:2245
__udp4_lib_rcv+0x701/0x2ca0 net/ipv4/udp.c:2301
udp_rcv+0x22/0x30 net/ipv4/udp.c:2482
ip_protocol_deliver_rcu+0x60/0x8f0 net/ipv4/ip_input.c:208
ip_local_deliver_finish+0x23b/0x390 net/ipv4/ip_input.c:234
NF_HOOK include/linux/netfilter.h:289 [inline]
NF_HOOK include/linux/netfilter.h:283 [inline]
ip_local_deliver+0x1e9/0x520 net/ipv4/ip_input.c:255
dst_input include/net/dst.h:450 [inline]
ip_rcv_finish+0x1e1/0x300 net/ipv4/ip_input.c:413
NF_HOOK include/linux/netfilter.h:289 [inline]
NF_HOOK include/linux/netfilter.h:283 [inline]
ip_rcv+0xe8/0x3f0 net/ipv4/ip_input.c:523
__netif_receive_skb_one_core+0x115/0x1a0 net/core/dev.c:4987
__netif_receive_skb+0x2c/0x1c0 net/core/dev.c:5099
netif_receive_skb_internal+0x117/0x660 net/core/dev.c:5202
napi_frags_finish net/core/dev.c:5769 [inline]
napi_gro_frags+0xade/0xd10 net/core/dev.c:5843
tun_get_user+0x2f24/0x3fb0 drivers/net/tun.c:1981
tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2027
call_write_iter include/linux/fs.h:1866 [inline]
do_iter_readv_writev+0x5e1/0x8e0 fs/read_write.c:681
do_iter_write fs/read_write.c:957 [inline]
do_iter_write+0x184/0x610 fs/read_write.c:938
vfs_writev+0x1b3/0x2f0 fs/read_write.c:1002
do_writev+0x15e/0x370 fs/read_write.c:1037
__do_sys_writev fs/read_write.c:1110 [inline]
__se_sys_writev fs/read_write.c:1107 [inline]
__x64_sys_writev+0x75/0xb0 fs/read_write.c:1107
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Fixes: 5271953cad31 ("rxrpc: Use the UDP encap_rcv hook")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
* handle data received on the local endpoint
* - may be called in interrupt context
*
- * The socket is locked by the caller and this prevents the socket from being
- * shut down and the local endpoint from going away, thus sk_user_data will not
- * be cleared until this function returns.
+ * [!] Note that as this is called from the encap_rcv hook, the socket is not
+ * held locked by the caller and nothing prevents sk_user_data on the UDP from
+ * being cleared in the middle of processing this function.
*
* Called with the RCU read lock held from the IP layer via UDP.
*/
int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
{
+ struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
struct rxrpc_connection *conn;
struct rxrpc_channel *chan;
struct rxrpc_call *call = NULL;
struct rxrpc_skb_priv *sp;
- struct rxrpc_local *local = udp_sk->sk_user_data;
struct rxrpc_peer *peer = NULL;
struct rxrpc_sock *rx = NULL;
unsigned int channel;
_enter("%p", udp_sk);
+ if (unlikely(!local)) {
+ kfree_skb(skb);
+ return 0;
+ }
if (skb->tstamp == 0)
skb->tstamp = ktime_get_real();
ret = -ENOMEM;
sock_error:
mutex_unlock(&rxnet->local_mutex);
- kfree(local);
+ if (local)
+ call_rcu(&local->rcu, rxrpc_local_rcu);
_leave(" = %d", ret);
return ERR_PTR(ret);
projects / openwrt / staging / blogic.git / commitdiff