netlink: fix potential deadlock in netlink_set_err()

syzbot reported a possible deadlock in netlink_set_err() [1]

A similar issue was fixed in commit 1d482e666b8e ("netlink: disable IRQs
for netlink_lock_table()") in netlink_lock_table()

This patch adds IRQ safety to netlink_set_err() and __netlink_diag_dump()
which were not covered by cited commit.

[1]

WARNING: possible irq lock inversion dependency detected
6.4.0-rc6-syzkaller-00240-g4e9f0ec38852 #0 Not tainted

syz-executor.2/23011 just changed the state of lock:
ffffffff8e1a7a58 (nl_table_lock){.+.?}-{2:2}, at: netlink_set_err+0x2e/0x3a0 net/netlink/af_netlink.c:1612
but this lock was taken by another, SOFTIRQ-safe lock in the past:
 (&local->queue_stop_reason_lock){..-.}-{2:2}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(nl_table_lock);
                               local_irq_disable();
                               lock(&local->queue_stop_reason_lock);
                               lock(nl_table_lock);
  <Interrupt>
    lock(&local->queue_stop_reason_lock);

 *** DEADLOCK ***

Fixes: 1d482e666b8e ("netlink: disable IRQs for netlink_lock_table()")
Reported-by: [email protected]
Link: https://syzkaller.appspot.com/bug?extid=a7d200a347f912723e5c
Link: https://lore.kernel.org/netdev/[email protected]/T/#u
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Johannes Berg <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

0 files changed, 0 insertions, 0 deletions