wifi: mac80211: check if the existing link config remains unchanged

[Syz report]
WARNING: CPU: 1 PID: 5067 at net/mac80211/rate.c:48 rate_control_rate_init+0x540/0x690 net/mac80211/rate.c:48
Modules linked in:
CPU: 1 PID: 5067 Comm: syz-executor413 Not tainted 6.7.0-rc3-syzkaller-00014-gdf60cee2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:rate_control_rate_init+0x540/0x690 net/mac80211/rate.c:48
Code: 48 c7 c2 00 46 0c 8c be 08 03 00 00 48 c7 c7 c0 45 0c 8c c6 05 70 79 0b 05 01 e8 1b a0 6f f7 e9 e0 fd ff ff e8 61 b3 8f f7 90 <0f> 0b 90 e9 36 ff ff ff e8 53 b3 8f f7 e8 5e 0b 78 f7 31 ff 89 c3
RSP: 0018:ffffc90003c57248 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888016bc4000 RCX: ffffffff89f7d519
RDX: ffff888076d43b80 RSI: ffffffff89f7d6df RDI: 0000000000000005
RBP: ffff88801daaae20 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000001
R13: 0000000000000000 R14: ffff888020030e20 R15: ffff888078f08000
FS:  0000555556b94380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005fdeb8 CR3: 0000000076d22000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 sta_apply_auth_flags.constprop.0+0x4b7/0x510 net/mac80211/cfg.c:1674
 sta_apply_parameters+0xaf1/0x16c0 net/mac80211/cfg.c:2002
 ieee80211_add_station+0x3fa/0x6c0 net/mac80211/cfg.c:2068
 rdev_add_station net/wireless/rdev-ops.h:201 [inline]
 nl80211_new_station+0x13ba/0x1a70 net/wireless/nl80211.c:7603
 genl_family_rcv_msg_doit+0x1fc/0x2e0 net/netlink/genetlink.c:972
 genl_family_rcv_msg net/netlink/genetlink.c:1052 [inline]
 genl_rcv_msg+0x561/0x800 net/netlink/genetlink.c:1067
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2545
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
 netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
 netlink_unicast+0x53b/0x810 net/netlink/af_netlink.c:1368
 netlink_sendmsg+0x93c/0xe40 net/netlink/af_netlink.c:1910
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0xd5/0x180 net/socket.c:745
 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2584
 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2638
 __sys_sendmsg+0x117/0x1e0 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

[Analysis]
It is inappropriate to make a link configuration change judgment on an
non-existent and non new link.

[Fix]
Quickly exit when there is a existent link and the link configuration has not
changed.

Fixes: b303835d ("wifi: mac80211: accept STA changes without link changes")
Reported-and-tested-by: syzbot+62d7eef57b09bfebcd84@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Link: https://msgid.link/tencent_DE67FF86DB92ED465489A36ECD2EDDCC8C06@qq.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -1788,10 +1788,10 @@ static int sta_link_apply_parameters(struct ieee80211_local *local,
 					  lockdep_is_held(&local->hw.wiphy->mtx));
 
 	/*
-	 * If there are no changes, then accept a link that doesn't exist,
+	 * If there are no changes, then accept a link that exist,
 	 * unless it's a new link.
 	 */
-	if (params->link_id < 0 && !new_link &&
+	if (params->link_id >= 0 && !new_link &&
 	    !params->link_mac && !params->txpwr_set &&
 	    !params->supported_rates_len &&
 	    !params->ht_capa && !params->vht_capa &&