[syzbot] [wireless?] WARNING in wiphy_register (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2281958e6007 Merge tag 'wireless-next-2026-05-06' of https..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=139f656a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f2b487b72ffad035
dashboard link: https://syzkaller.appspot.com/bug?extid=2002864e6c6895cb0ac3
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1452fb48580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=179f656a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4df17f60254b/disk-2281958e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1e93157edd25/vmlinux-2281958e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/60dbf6a0a81c/bzImage-2281958e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+200286...@syzkaller.appspotmail.com

------------[ cut here ]------------
(wiphy->interface_modes & BIT(NL80211_IFTYPE_NAN_DATA)) && (!wiphy->nan_capa.phy.ht.ht_supported || wiphy->n_radio > 1)
WARNING: net/wireless/core.c:885 at wiphy_register+0x58a/0x2fe0 net/wireless/core.c:884, CPU#0: syz.0.17/5835
Modules linked in:
CPU: 0 UID: 0 PID: 5835 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:wiphy_register+0x58a/0x2fe0 net/wireless/core.c:884
Code: 00 00 e8 49 8f d4 f6 90 0f 0b 90 e9 67 0a 00 00 e8 3b 8f d4 f6 e9 59 0a 00 00 e8 31 8f d4 f6 e9 eb 00 00 00 e8 27 8f d4 f6 90 <0f> 0b 90 e9 45 0a 00 00 44 89 f8 24 06 0f b6 d8 31 ff 89 de e8 0d
RSP: 0018:ffffc90003236860 EFLAGS: 00010293
RAX: ffffffff8af13fe2 RBX: 0000000000000004 RCX: ffff88802ed60000
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001
RBP: ffffc900032369f0 R08: ffff8880582b0faf R09: 1ffff1100b0561f5
R10: dffffc0000000000 R11: ffffed100b0561f6 R12: ffff8880582b0740
R13: dffffc0000000000 R14: ffffffff8d002990 R15: ffff8880582b0804
FS: 0000555593855500(0000) GS:ffff888125289000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007eff2e872700 CR3: 0000000075672000 CR4: 00000000003526f0
Call Trace:
<TASK>
ieee80211_register_hw+0x3c53/0x4910 net/mac80211/main.c:1627
mac80211_hwsim_new_radio+0x3327/0x57e0 drivers/net/wireless/virtual/mac80211_hwsim_main.c:6047
hwsim_new_radio_nl+0xe20/0x26e0 drivers/net/wireless/virtual/mac80211_hwsim_main.c:6832
genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2551
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7eff2e99cdd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd72c5edf8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007eff2ec15fa0 RCX: 00007eff2e99cdd9
RDX: 0000000000000000 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007eff2ea32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007eff2ec15fac R14: 00007eff2ec15fa0 R15: 00007eff2ec15fa0
</TASK>


---
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[syzbot]

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***

Subject: [PATCH] wifi: mac80211_hwsim: reject NAN on multi-radio wiphys
Author: karti...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main


When userspace creates a new hwsim radio with both
HWSIM_ATTR_MULTI_RADIO and HWSIM_ATTR_SUPPORT_NAN_DEVICE,
hwsim_new_radio_nl() sets BIT(NL80211_IFTYPE_NAN_DATA) in
wiphy->interface_modes while configuring the wiphy with
n_radio > 1. This violates the invariant checked in
wiphy_register():

(interface_modes & BIT(NL80211_IFTYPE_NAN_DATA)) &&
(!nan_capa.phy.ht.ht_supported || n_radio > 1)

triggering a WARN reachable from userspace via genetlink.
With panic_on_warn this becomes a denial of service.

Refuse the combination at parse time with -EINVAL and an
extack message, matching the cfg80211 constraint that NAN
is not supported on multi-radio wiphys.

Reported-by: syzbot+200286...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=2002864e6c6895cb0ac3
Signed-off-by: Deepanshu Kartikey <karti...@gmail.com>
---
drivers/net/wireless/virtual/mac80211_hwsim_main.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/virtual/mac80211_hwsim_main.c b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
index dc9775cd9f54..a625a9e3caa7 100644
--- a/drivers/net/wireless/virtual/mac80211_hwsim_main.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
@@ -6766,9 +6766,15 @@ static int hwsim_new_radio_nl(struct sk_buff *msg, struct genl_info *info)
param.p2p_device = true;
}

- if (param.nan_device)
+ if (param.nan_device) {
+ if (param.multi_radio) {
+ NL_SET_ERR_MSG(info->extack,
+ "NAN is not supported on multi-radio wiphys");
+ return -EINVAL;
+ }
param.iftypes |= BIT(NL80211_IFTYPE_NAN) |
BIT(NL80211_IFTYPE_NAN_DATA);
+ }

if (info->attrs[HWSIM_ATTR_CIPHER_SUPPORT]) {
u32 len = nla_len(info->attrs[HWSIM_ATTR_CIPHER_SUPPORT]);
--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+200286...@syzkaller.appspotmail.com
Tested-by: syzbot+200286...@syzkaller.appspotmail.com

Tested on:

commit: 6a4c4656 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main
console output: https://syzkaller.appspot.com/x/log.txt?x=107bfb48580000

kernel config: https://syzkaller.appspot.com/x/.config?x=f2b487b72ffad035
dashboard link: https://syzkaller.appspot.com/bug?extid=2002864e6c6895cb0ac3
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=11bd6636580000

Note: testing is done by a robot and is best-effort only.