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7f041ee8ef
[ Upstream commit 28259bac7f1dde06d8ba324e222bbec9d4e92f2b ]
Syzbot reported the suspecious RCU usage in nexthop_fib6_nh() when
called from ipv6_route_seq_show(). The reason is ipv6_route_seq_start()
calls rcu_read_lock_bh(), while nexthop_fib6_nh() calls
rcu_dereference_rtnl().
The fix proposed is to add a variant of nexthop_fib6_nh() to use
rcu_dereference_bh_rtnl() for ipv6_route_seq_show().
The reported trace is as follows:
./include/net/nexthop.h:416 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syz-executor.0/17895:
at: seq_read+0x71/0x12a0 fs/seq_file.c:169
at: seq_file_net include/linux/seq_file_net.h:19 [inline]
at: ipv6_route_seq_start+0xaf/0x300 net/ipv6/ip6_fib.c:2616
stack backtrace:
CPU: 1 PID: 17895 Comm: syz-executor.0 Not tainted 4.15.0-syzkaller #0
Call Trace:
[<ffffffff849edf9e>] __dump_stack lib/dump_stack.c:17 [inline]
[<ffffffff849edf9e>] dump_stack+0xd8/0x147 lib/dump_stack.c:53
[<ffffffff8480b7fa>] lockdep_rcu_suspicious+0x153/0x15d kernel/locking/lockdep.c:5745
[<ffffffff8459ada6>] nexthop_fib6_nh include/net/nexthop.h:416 [inline]
[<ffffffff8459ada6>] ipv6_route_native_seq_show net/ipv6/ip6_fib.c:2488 [inline]
[<ffffffff8459ada6>] ipv6_route_seq_show+0x436/0x7a0 net/ipv6/ip6_fib.c:2673
[<ffffffff81c556df>] seq_read+0xccf/0x12a0 fs/seq_file.c:276
[<ffffffff81dbc62c>] proc_reg_read+0x10c/0x1d0 fs/proc/inode.c:231
[<ffffffff81bc28ae>] do_loop_readv_writev fs/read_write.c:714 [inline]
[<ffffffff81bc28ae>] do_loop_readv_writev fs/read_write.c:701 [inline]
[<ffffffff81bc28ae>] do_iter_read+0x49e/0x660 fs/read_write.c:935
[<ffffffff81bc81ab>] vfs_readv+0xfb/0x170 fs/read_write.c:997
[<ffffffff81c88847>] kernel_readv fs/splice.c:361 [inline]
[<ffffffff81c88847>] default_file_splice_read+0x487/0x9c0 fs/splice.c:416
[<ffffffff81c86189>] do_splice_to+0x129/0x190 fs/splice.c:879
[<ffffffff81c86f66>] splice_direct_to_actor+0x256/0x890 fs/splice.c:951
[<ffffffff81c8777d>] do_splice_direct+0x1dd/0x2b0 fs/splice.c:1060
[<ffffffff81bc4747>] do_sendfile+0x597/0xce0 fs/read_write.c:1459
[<ffffffff81bca205>] SYSC_sendfile64 fs/read_write.c:1520 [inline]
[<ffffffff81bca205>] SyS_sendfile64+0x155/0x170 fs/read_write.c:1506
[<ffffffff81015fcf>] do_syscall_64+0x1ff/0x310 arch/x86/entry/common.c:305
[<ffffffff84a00076>] entry_SYSCALL_64_after_hwframe+0x42/0xb7
Fixes:
|
||
|---|---|---|
| .. | ||
| ila | ||
| netfilter | ||
| addrconf_core.c | ||
| addrconf.c | ||
| addrlabel.c | ||
| af_inet6.c | ||
| ah6.c | ||
| anycast.c | ||
| calipso.c | ||
| datagram.c | ||
| esp6_offload.c | ||
| esp6.c | ||
| exthdrs_core.c | ||
| exthdrs_offload.c | ||
| exthdrs.c | ||
| fib6_notifier.c | ||
| fib6_rules.c | ||
| fou6.c | ||
| icmp.c | ||
| inet6_connection_sock.c | ||
| inet6_hashtables.c | ||
| ip6_checksum.c | ||
| ip6_fib.c | ||
| ip6_flowlabel.c | ||
| ip6_gre.c | ||
| ip6_icmp.c | ||
| ip6_input.c | ||
| ip6_offload.c | ||
| ip6_offload.h | ||
| ip6_output.c | ||
| ip6_tunnel.c | ||
| ip6_udp_tunnel.c | ||
| ip6_vti.c | ||
| ip6mr.c | ||
| ipcomp6.c | ||
| ipv6_sockglue.c | ||
| Kconfig | ||
| Makefile | ||
| mcast_snoop.c | ||
| mcast.c | ||
| mip6.c | ||
| ndisc.c | ||
| netfilter.c | ||
| output_core.c | ||
| ping.c | ||
| proc.c | ||
| protocol.c | ||
| raw.c | ||
| reassembly.c | ||
| route.c | ||
| rpl_iptunnel.c | ||
| rpl.c | ||
| seg6_hmac.c | ||
| seg6_iptunnel.c | ||
| seg6_local.c | ||
| seg6.c | ||
| sit.c | ||
| syncookies.c | ||
| sysctl_net_ipv6.c | ||
| tcp_ipv6.c | ||
| tcpv6_offload.c | ||
| tunnel6.c | ||
| udp_impl.h | ||
| udp_offload.c | ||
| udp.c | ||
| udplite.c | ||
| xfrm6_input.c | ||
| xfrm6_output.c | ||
| xfrm6_policy.c | ||
| xfrm6_protocol.c | ||
| xfrm6_state.c | ||
| xfrm6_tunnel.c | ||