SMC ioctl processing requires the sock lock to work properly in
all thinkable scenarios.
Problem has been found with RaceFuzzer and fixes:
KASAN: null-ptr-deref Read in smc_ioctl
Reported-by: Byoungyoung Lee <lifeasageek@gmail.com> Reported-by: syzbot+35b2c5aa76fd398b9fd4@syzkaller.appspotmail.com Signed-off-by: Ursula Braun <ubraun@linux.ibm.com> Reviewed-by: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>