• Eric Dumazet's avatar
    net: silence KCSAN warnings around sk_add_backlog() calls · 8265792b
    Eric Dumazet authored
    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: default avatarEric Dumazet <edumazet@google.com>
    Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
    Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
    8265792b
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