CVE-2022-49662: ipv6: fix lockdep splat in in6_dump_addrs()

In the Linux kernel, the following vulnerability has been resolved:

ipv6: fix lockdep splat in in6dumpaddrs()

As reported by syzbot, we should not use rcudereference() when rcureadlock() is not held.

WARNING: suspicious RCU usage 5.19.0-rc2-syzkaller #0 Not tainted

net/ipv6/addrconf.c:5175 suspicious rcudereferencecheck() usage!

other info that might help us debug this:

rcuscheduleractive = 2, debuglocks = 1 1 lock held by syz-executor326/3617: #0: ffffffff8d5848e8 (rtnlmutex){+.+.}-{3:3}, at: netlinkdump+0xae/0xc20 net/netlink/afnetlink.c:2223

stack backtrace: CPU: 0 PID: 3617 Comm: syz-executor326 Not tainted 5.19.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> dumpstack lib/dumpstack.c:88 [inline] dumpstacklvl+0xcd/0x134 lib/dumpstack.c:106 in6dumpaddrs+0x12d1/0x1790 net/ipv6/addrconf.c:5175 inet6dumpaddr+0x9c1/0xb50 net/ipv6/addrconf.c:5300 netlinkdump+0x541/0xc20 net/netlink/afnetlink.c:2275 netlinkdumpstart+0x647/0x900 net/netlink/afnetlink.c:2380 netlinkdumpstart include/linux/netlink.h:245 [inline] rtnetlinkrcvmsg+0x73e/0xc90 net/core/rtnetlink.c:6046 netlinkrcvskb+0x153/0x420 net/netlink/afnetlink.c:2501 netlinkunicastkernel net/netlink/afnetlink.c:1319 [inline] netlinkunicast+0x543/0x7f0 net/netlink/afnetlink.c:1345 netlinksendmsg+0x917/0xe10 net/netlink/afnetlink.c:1921 socksendmsgnosec net/socket.c:714 [inline] socksendmsg+0xcf/0x120 net/socket.c:734 syssendmsg+0x6eb/0x810 net/socket.c:2492 syssendmsg+0xf3/0x170 net/socket.c:2546 syssendmsg net/socket.c:2575 [inline] dosyssendmsg net/socket.c:2584 [inline] sesyssendmsg net/socket.c:2582 [inline] x64syssendmsg+0x132/0x220 net/socket.c:2582 dosyscallx64 arch/x86/entry/common.c:50 [inline] dosyscall64+0x35/0xb0 arch/x86/entry/common.c:80 entrySYSCALL64afterhwframe+0x46/0xb0