6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit fce92af1c29d90184dfec638b5738831097d66e9 ]
syzbot complained about a data-race in fib_table_lookup() [1]
Add appropriate annotations to document it.
[1] BUG: KCSAN: data-race in fib_release_info / fib_table_lookup
write to 0xffff888150f31744 of 1 bytes by task 1189 on cpu 0: fib_release_info+0x3a0/0x460 net/ipv4/fib_semantics.c:281 fib_table_delete+0x8d2/0x900 net/ipv4/fib_trie.c:1777 fib_magic+0x1c1/0x1f0 net/ipv4/fib_frontend.c:1106 fib_del_ifaddr+0x8cf/0xa60 net/ipv4/fib_frontend.c:1317 fib_inetaddr_event+0x77/0x200 net/ipv4/fib_frontend.c:1448 notifier_call_chain kernel/notifier.c:93 [inline] blocking_notifier_call_chain+0x90/0x200 kernel/notifier.c:388 __inet_del_ifa+0x4df/0x800 net/ipv4/devinet.c:432 inet_del_ifa net/ipv4/devinet.c:469 [inline] inetdev_destroy net/ipv4/devinet.c:322 [inline] inetdev_event+0x553/0xaf0 net/ipv4/devinet.c:1606 notifier_call_chain kernel/notifier.c:93 [inline] raw_notifier_call_chain+0x6b/0x1c0 kernel/notifier.c:461 call_netdevice_notifiers_info net/core/dev.c:1962 [inline] call_netdevice_notifiers_mtu+0xd2/0x130 net/core/dev.c:2037 dev_set_mtu_ext+0x30b/0x3e0 net/core/dev.c:8673 do_setlink+0x5be/0x2430 net/core/rtnetlink.c:2837 rtnl_setlink+0x255/0x300 net/core/rtnetlink.c:3177 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6445 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2549 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6463 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1914 sock_sendmsg_nosec net/socket.c:725 [inline] sock_sendmsg net/socket.c:748 [inline] sock_write_iter+0x1aa/0x230 net/socket.c:1129 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860 vfs_writev+0x1a8/0x320 fs/read_write.c:933 do_writev+0xf8/0x220 fs/read_write.c:976 __do_sys_writev fs/read_write.c:1049 [inline] __se_sys_writev fs/read_write.c:1046 [inline] __x64_sys_writev+0x45/0x50 fs/read_write.c:1046 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
read to 0xffff888150f31744 of 1 bytes by task 21839 on cpu 1: fib_table_lookup+0x2bf/0xd50 net/ipv4/fib_trie.c:1585 fib_lookup include/net/ip_fib.h:383 [inline] ip_route_output_key_hash_rcu+0x38c/0x12c0 net/ipv4/route.c:2751 ip_route_output_key_hash net/ipv4/route.c:2641 [inline] __ip_route_output_key include/net/route.h:134 [inline] ip_route_output_flow+0xa6/0x150 net/ipv4/route.c:2869 send4+0x1e7/0x500 drivers/net/wireguard/socket.c:61 wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175 wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51 process_one_work+0x434/0x860 kernel/workqueue.c:2600 worker_thread+0x5f2/0xa10 kernel/workqueue.c:2751 kthread+0x1d7/0x210 kernel/kthread.c:389 ret_from_fork+0x2e/0x40 arch/x86/kernel/process.c:145 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
value changed: 0x00 -> 0x01
Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 21839 Comm: kworker/u4:18 Tainted: G W 6.5.0-syzkaller #0
Fixes: dccd9ecc3744 ("ipv4: Do not use dead fib_info entries.") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: David Ahern dsahern@kernel.org Link: https://lore.kernel.org/r/20230830095520.1046984-1-edumazet@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/fib_semantics.c | 5 ++++- net/ipv4/fib_trie.c | 3 ++- 2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index 3bb890a40ed73..3b6e6bc80dc1c 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -278,7 +278,8 @@ void fib_release_info(struct fib_info *fi) hlist_del(&nexthop_nh->nh_hash); } endfor_nexthops(fi) } - fi->fib_dead = 1; + /* Paired with READ_ONCE() from fib_table_lookup() */ + WRITE_ONCE(fi->fib_dead, 1); fib_info_put(fi); } spin_unlock_bh(&fib_info_lock); @@ -1581,6 +1582,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg, link_it: ofi = fib_find_info(fi); if (ofi) { + /* fib_table_lookup() should not see @fi yet. */ fi->fib_dead = 1; free_fib_info(fi); refcount_inc(&ofi->fib_treeref); @@ -1619,6 +1621,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
failure: if (fi) { + /* fib_table_lookup() should not see @fi yet. */ fi->fib_dead = 1; free_fib_info(fi); } diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c index 74d403dbd2b4e..d13fb9e76b971 100644 --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -1582,7 +1582,8 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp, if (fa->fa_dscp && inet_dscp_to_dsfield(fa->fa_dscp) != flp->flowi4_tos) continue; - if (fi->fib_dead) + /* Paired with WRITE_ONCE() in fib_release_info() */ + if (READ_ONCE(fi->fib_dead)) continue; if (fa->fa_info->fib_scope < flp->flowi4_scope) continue;