=====================================
[ BUG: bad unlock balance detected! ]
4.9.0-rc3+ #336 Not tainted
-------------------------------------
syz-executor/4018 is trying to release lock ([ 36.220068] nl_table_lock
) at:
[<ffffffff82dc8683>] netlink_diag_dump+0x1a3/0x250 net/netlink/diag.c:182
but there are no more locks to release!
other info that might help us debug this:
3 locks held by syz-executor/4018:
#0: [ 36.220068] (
sock_diag_mutex[ 36.220068] ){+.+.+.}
, at: [ 36.220068] [<ffffffff82c3873b>] sock_diag_rcv+0x1b/0x40
#1: [ 36.220068] (
sock_diag_table_mutex[ 36.220068] ){+.+.+.}
, at: [ 36.220068] [<ffffffff82c38e00>] sock_diag_rcv_msg+0x140/0x3a0
#2: [ 36.220068] (
nlk->cb_mutex[ 36.220068] ){+.+.+.}
, at: [ 36.220068] [<ffffffff82db6600>] netlink_dump+0x50/0xac0
stack backtrace:
CPU: 1 PID: 4018 Comm: syz-executor Not tainted 4.9.0-rc3+ #336
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
ffff8800645df688 ffffffff81b46934 ffffffff84eb3e78 ffff88006ad85800
ffffffff82dc8683 ffffffff84eb3e78 ffff8800645df6b8 ffffffff812043ca
dffffc0000000000 ffff88006ad85ff8 ffff88006ad85fd0 00000000ffffffff
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff81b46934>] dump_stack+0xb3/0x10f lib/dump_stack.c:51
[<ffffffff812043ca>] print_unlock_imbalance_bug+0x17a/0x1a0
kernel/locking/lockdep.c:3388
[< inline >] __lock_release kernel/locking/lockdep.c:3512
[<ffffffff8120cfd8>] lock_release+0x8e8/0xc60 kernel/locking/lockdep.c:3765
[< inline >] __raw_read_unlock ./include/linux/rwlock_api_smp.h:225
[<ffffffff83fc001a>] _raw_read_unlock+0x1a/0x30 kernel/locking/spinlock.c:255
[<ffffffff82dc8683>] netlink_diag_dump+0x1a3/0x250 net/netlink/diag.c:182
[<ffffffff82db6947>] netlink_dump+0x397/0xac0 net/netlink/af_netlink.c:2110
Fixes: ad202074320c ("netlink: Use rhashtable walk interface in diag dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
---
net/netlink/diag.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
@@ -178,11 +178,8 @@ static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
}
cb->args[1] = i;
} else {
- if (req->sdiag_protocol >= MAX_LINKS) {
- read_unlock(&nl_table_lock);
- rcu_read_unlock();
+ if (req->sdiag_protocol >= MAX_LINKS)
return -ENOENT;
- }
err = __netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
}
From: Eric Dumazet <edumazet@google.com> A recent commit removed locking from netlink_diag_dump() but forgot one error case.