Subject: [syzbot] WARNING in ieee80211_offchannel_return

From: syzbot <[email-masked]>
Date: Wed, 21 Jul 2021 19:10:25 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    23d2b94043ca igmp: Add ip_mc_list lock in ip_check_mc_rcu
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16cde812300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=da140227e4f25b17
dashboard link: https://syzkaller.appspot.com/bug?extid=4c10031c63f173ea1dfc

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

------------[ cut here ]------------
WARNING: CPU: 0 PID: 8308 at net/mac80211/offchannel.c:136 ieee80211_offchannel_return+0x3e6/0x4a0 net/mac80211/offchannel.c:136
Modules linked in:
CPU: 0 PID: 8308 Comm: syz-executor.4 Tainted: G        W         5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ieee80211_offchannel_return+0x3e6/0x4a0 net/mac80211/offchannel.c:136
Code: 00 48 01 c6 e8 4b 04 e9 f8 e9 0e ff ff ff e8 01 96 f9 f8 31 d2 48 89 de 4c 89 e7 e8 34 b3 15 00 e9 f7 fe ff ff e8 ea 95 f9 f8 <0f> 0b e9 6c ff ff ff e8 ae 1d 40 f9 e9 51 fc ff ff 48 89 df e8 d1
RSP: 0018:ffffc900020f7230 EFLAGS: 00010212
RAX: 00000000000006ed RBX: 0000000000000001 RCX: ffffc90012282000
RDX: 0000000000040000 RSI: ffffffff887bf386 RDI: 0000000000000003
RBP: ffff888075980d20 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff887beffc R11: 0000000000000000 R12: ffff88807443c800
R13: ffff888075982968 R14: 0000000000000000 R15: 0000000000000001
FS:  00007f1a294ca700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f02e832aab4 CR3: 0000000081623000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __ieee80211_scan_completed+0x776/0xef0 net/mac80211/scan.c:470
 ieee80211_scan_cancel+0x165/0x9b0 net/mac80211/scan.c:1277
 ieee80211_do_stop+0x1863/0x2050 net/mac80211/iface.c:384
 ieee80211_runtime_change_iftype net/mac80211/iface.c:1656 [inline]
 ieee80211_if_change_type+0x383/0x840 net/mac80211/iface.c:1694
 ieee80211_change_iface+0x26/0x210 net/mac80211/cfg.c:157
 rdev_change_virtual_intf net/wireless/rdev-ops.h:69 [inline]
 cfg80211_change_iface+0x335/0xf60 net/wireless/util.c:1073
 nl80211_set_interface+0x65c/0x8d0 net/wireless/nl80211.c:3923
 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:739
 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
 genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:800
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:703 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:723
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2392
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2446
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2475
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1a294ca188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000006
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffe92760a3f R14: 00007f1a294ca300 R15: 0000000000022000

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