Messages in this thread | | | Date | Mon, 2 Nov 2015 13:31:13 -0800 | Subject | Re: net: lockdep warning in ip_mc_msfget (net/ipv4/igmp.c:2400) | From | Cong Wang <> |
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On Mon, Nov 2, 2015 at 7:22 AM, Sasha Levin <sasha.levin@oracle.com> wrote: > Hi all, > > While fuzzing with syzkaller inside a KVM tools guest running the latest -next, I saw > the following warning: > > [ 2391.993558] ====================================================== > [ 2391.995441] [ INFO: possible circular locking dependency detected ] > [ 2391.995771] 4.3.0-rc6-next-20151022-sasha-00042-g2b253a1-dirty #2618 Not tainted > [ 2391.995771] ------------------------------------------------------- > [ 2391.995771] syzkaller_execu/14105 is trying to acquire lock: > [ 2391.995771] (rtnl_mutex){+.+.+.}, at: rtnl_lock (net/core/rtnetlink.c:71) > [ 2391.995771] Mutex: counter: 1 owner: None > [ 2391.995771] > [ 2391.995771] but task is already holding lock: > [ 2391.995771] (sk_lock-AF_INET){+.+.+.}, at: do_ip_getsockopt (net/ipv4/ip_sockglue.c:1274) > [ 2391.995771] > [ 2391.995771] which lock already depends on the new lock. > [ 2391.995771] > [ 2391.995771] > [ 2391.995771] the existing dependency chain (in reverse order) is: > [ 2391.995771] -> #1 (sk_lock-AF_INET){+.+.+.}: > [ 2391.995771] lock_acquire (kernel/locking/lockdep.c:3620) > [ 2391.995771] lock_sock_nested (include/linux/bottom_half.h:31 net/core/sock.c:2411) > [ 2391.995771] do_ip_setsockopt.isra.9 (net/ipv4/ip_sockglue.c:623) > [ 2391.995771] ip_setsockopt (net/ipv4/ip_sockglue.c:1202) > [ 2391.995771] ffffffffffffff, 0x0) > [ 2391.995771] sock_common_setsockopt (net/core/sock.c:2610) > [ 2391.995771] SyS_setsockopt (net/socket.c:1756 net/socket.c:1736) > [ 2391.995771] entry_SYSCALL_64_fastpath (arch/x86/entry/entry_64.S:188) > [ 2391.995771] -> #0 (rtnl_mutex){+.+.+.}: > [ 2391.995771] __lock_acquire (kernel/locking/lockdep.c:1877 kernel/locking/lockdep.c:1982 kernel/locking/lockdep.c:2168 kernel/locking/lockdep.c:3239) > [ 2391.995771] lock_acquire (kernel/locking/lockdep.c:3620) > [ 2391.995771] mutex_lock_nested (kernel/locking/mutex.c:526 kernel/locking/mutex.c:618) > [ 2391.995771] rtnl_lock (net/core/rtnetlink.c:71) > [ 2391.995771] ip_mc_msfget (net/ipv4/igmp.c:2400) > [ 2391.995771] do_ip_getsockopt (net/ipv4/ip_sockglue.c:1401) > [ 2391.995771] ip_getsockopt (net/ipv4/ip_sockglue.c:1498) > [ 2391.995771] raw_getsockopt (net/ipv4/raw.c:851) > [ 2391.995771] sock_common_getsockopt (net/core/sock.c:2569) > [ 2391.995771] SyS_getsockopt (net/socket.c:1787 net/socket.c:1770) > [ 2391.995771] entry_SYSCALL_64_fastpath (arch/x86/entry/entry_64.S:188) > [ 2391.995771] > [ 2391.995771] other info that might help us debug this: > [ 2391.995771] > [ 2391.995771] Possible unsafe locking scenario: > [ 2391.995771] > [ 2391.995771] CPU0 CPU1 > [ 2391.995771] ---- ---- > [ 2391.995771] lock(sk_lock-AF_INET); > [ 2391.995771] lock(rtnl_mutex); > [ 2391.995771] lock(sk_lock-AF_INET); > [ 2391.995771] lock(rtnl_mutex); > [ 2391.995771] > [ 2391.995771] *** DEADLOCK *** > [ 2391.995771] > [ 2391.995771] 1 lock held by syzkaller_execu/14105: > [ 2391.995771] #0: (sk_lock-AF_INET){+.+.+.}, at: do_ip_getsockopt (net/ipv4/ip_sockglue.c:1274) > [ 2391.995771] > [ 2391.995771] stack backtrace: > [ 2391.995771] CPU: 1 PID: 14105 Comm: syzkaller_execu Not tainted 4.3.0-rc6-next-20151022-sasha-00042-g2b253a1-dirty #2618 > [ 2391.995771] 0000000000000001 00000000c179c8c9 ffff8800a403f550 ffffffffade32a2b > [ 2391.995771] ffffffffbb7f5a50 ffffffffbb84a4a0 ffffffffbb7f5a50 ffff8800a403f5a0 > [ 2391.995771] ffffffffac43fca8 ffff8800a403f690 00000000a3e18000 ffff8800a3e18000 > [ 2391.995771] Call Trace: > [ 2391.995771] dump_stack (lib/dump_stack.c:52) > [ 2391.995771] print_circular_bug (kernel/locking/lockdep.c:1250) > [ 2391.995771] __lock_acquire (kernel/locking/lockdep.c:1877 kernel/locking/lockdep.c:1982 kernel/locking/lockdep.c:2168 kernel/locking/lockdep.c:3239) > [ 2391.995771] lock_acquire (kernel/locking/lockdep.c:3620) > [ 2391.995771] mutex_lock_nested (kernel/locking/mutex.c:526 kernel/locking/mutex.c:618) > [ 2391.995771] rtnl_lock (net/core/rtnetlink.c:71) > [ 2391.995771] ip_mc_msfget (net/ipv4/igmp.c:2400) > [ 2391.995771] do_ip_getsockopt (net/ipv4/ip_sockglue.c:1401) > [ 2391.995771] ip_getsockopt (net/ipv4/ip_sockglue.c:1498) > [ 2391.995771] raw_getsockopt (net/ipv4/raw.c:851) > [ 2391.995771] sock_common_getsockopt (net/core/sock.c:2569) > [ 2391.995771] SyS_getsockopt (net/socket.c:1787 net/socket.c:1770) > [ 2391.995771] entry_SYSCALL_64_fastpath (arch/x86/entry/entry_64.S:188)
Good catch!
This is probably introduced by:
commit baf606d9c9b12517e47e0d1370e8aa9f7323f210 Author: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Date: Wed Mar 18 14:50:42 2015 -0300
ipv4,ipv6: grab rtnl before locking the socket
I am thinking what is the right way to fix it...
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