net: nfc: llcp: Add lock when modifying device list

net: nfc: llcp: Add lock when modifying device list

The device list needs its associated lock held when modifying it, or the
list could become corrupted, as syzbot discovered.

Reported-and-tested-by: syzbot+c1d0a03d305972dbbe14@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c1d0a03d305972dbbe14
Signed-off-by: Jeremy Cline <jeremy@jcline.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Fixes: 6709d4b7bc2e ("net: nfc: Fix use-after-free caused by nfc_llcp_find_local")
Link: https://lore.kernel.org/r/20230908235853.1319596-1-jeremy@jcline.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>