[syzbot] [wireless?] WARNING in ieee80211_sta_current_bw

[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=1513e696580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f2b487b72ffad035
dashboard link: https://syzkaller.appspot.com/bug?extid=e2a0da81361722f4df3b
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

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+e2a0da...@syzkaller.appspotmail.com

------------[ cut here ]------------
1
WARNING: ./include/net/mac80211.h:8114 at ieee80211_chan_width_to_rx_bw include/net/mac80211.h:8114 [inline], CPU#1: syz.4.4769/22510
WARNING: ./include/net/mac80211.h:8114 at ieee80211_sta_current_bw_tx_to_sta net/mac80211/sta_info.c:3719 [inline], CPU#1: syz.4.4769/22510
WARNING: ./include/net/mac80211.h:8114 at ieee80211_sta_current_bw+0x36d/0x510 net/mac80211/sta_info.c:3745, CPU#1: syz.4.4769/22510
Modules linked in:
CPU: 1 UID: 0 PID: 22510 Comm: syz.4.4769 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:ieee80211_chan_width_to_rx_bw include/net/mac80211.h:8114 [inline]
RIP: 0010:ieee80211_sta_current_bw_tx_to_sta net/mac80211/sta_info.c:3719 [inline]
RIP: 0010:ieee80211_sta_current_bw+0x36d/0x510 net/mac80211/sta_info.c:3745
Code: 00 00 00 eb 49 41 83 fe 05 74 30 41 83 fe 0d 75 13 e8 47 8f af f6 b8 04 00 00 00 eb 31 e8 3b 8f af f6 eb 28 e8 34 8f af f6 90 <0f> 0b 90 eb 1d e8 29 8f af f6 b8 02 00 00 00 eb 13 e8 1d 8f af f6
RSP: 0018:ffffc90006f4eed8 EFLAGS: 00010283
RAX: ffffffff8b161cfc RBX: 1ffff1100d1da030 RCX: 0000000000080000
RDX: ffffc9000e5d2000 RSI: 0000000000000e31 RDI: 0000000000000e32
RBP: 0000000000000004 R08: ffff888054ad5c40 R09: 0000000000000007
R10: 000000000000000d R11: 0000000000000002 R12: ffff888068ed0180
R13: dffffc0000000000 R14: 0000000000000007 R15: 0000000000000000
FS: 00007fe58f5f66c0(0000) GS:ffff888125389000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2c8823 CR3: 0000000038486000 CR4: 00000000003526f0
Call Trace:
<TASK>
ieee80211_chan_bw_change+0x459/0x740 net/mac80211/chan.c:719
_ieee80211_recalc_chanctx_min_def net/mac80211/chan.c:758 [inline]
ieee80211_recalc_chanctx_min_def+0x36/0x70 net/mac80211/chan.c:770
ieee80211_recalc_min_chandef+0x491/0x580 net/mac80211/util.c:2501
sta_info_insert_finish net/mac80211/sta_info.c:946 [inline]
sta_info_insert_rcu+0x15da/0x26b0 net/mac80211/sta_info.c:1029
sta_info_insert+0x16/0xc0 net/mac80211/sta_info.c:1034
ieee80211_add_station+0x4c7/0x710 net/mac80211/cfg.c:2666
rdev_add_station+0xfc/0x290 net/wireless/rdev-ops.h:201
nl80211_new_station+0x1cab/0x2130 net/wireless/nl80211.c:9490
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: 0033:0x7fe59139cdd9
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:00007fe58f5f6028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe591616090 RCX: 00007fe59139cdd9
RDX: 0000000000000000 RSI: 0000200000001080 RDI: 0000000000000006
RBP: 00007fe591432d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe591616128 R14: 00007fe591616090 R15: 00007fff2b0f3978
</TASK>


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[Lachlan Hodges]

> WARNING: ./include/net/mac80211.h:8114 at ieee80211_chan_width_to_rx_bw include/net/mac80211.h:8114 [inline], CPU#1: syz.4.4769/22510
> WARNING: ./include/net/mac80211.h:8114 at ieee80211_sta_current_bw_tx_to_sta net/mac80211/sta_info.c:3719 [inline], CPU#1: syz.4.4769/22510
> WARNING: ./include/net/mac80211.h:8114 at ieee80211_sta_current_bw+0x36d/0x510 net/mac80211/sta_info.c:3745, CPU#1: syz.4.4769/22510
> Modules linked in:
> CPU: 1 UID: 0 PID: 22510 Comm: syz.4.4769 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
> RIP: 0010:ieee80211_chan_width_to_rx_bw include/net/mac80211.h:8114 [inline]
> RIP: 0010:ieee80211_sta_current_bw_tx_to_sta net/mac80211/sta_info.c:3719 [inline]
> RIP: 0010:ieee80211_sta_current_bw+0x36d/0x510 net/mac80211/sta_info.c:3745
> Code: 00 00 00 eb 49 41 83 fe 05 74 30 41 83 fe 0d 75 13 e8 47 8f af f6 b8 04 00 00 00 eb 31 e8 3b 8f af f6 eb 28 e8 34 8f af f6 90 <0f> 0b 90 eb 1d e8 29 8f af f6 b8 02 00 00 00 eb 13 e8 1d 8f af f6
> RSP: 0018:ffffc90006f4eed8 EFLAGS: 00010283
> RAX: ffffffff8b161cfc RBX: 1ffff1100d1da030 RCX: 0000000000080000
> RDX: ffffc9000e5d2000 RSI: 0000000000000e31 RDI: 0000000000000e32
> RBP: 0000000000000004 R08: ffff888054ad5c40 R09: 0000000000000007
> R10: 000000000000000d R11: 0000000000000002 R12: ffff888068ed0180
> R13: dffffc0000000000 R14: 0000000000000007 R15: 0000000000000000
> FS: 00007fe58f5f66c0(0000) GS:ffff888125389000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000110c2c8823 CR3: 0000000038486000 CR4: 00000000003526f0

This looks to be 10MHz given R14 = 7 which seems to be the operand
being compared I think. The 2 patches I sent the other week should
fix this occuring for any S1G bandwidths, not sure about 5 and 10MHz.

Atleast for this situation, it would be the same - we don't wanna
recalc the mindef for 5 and 10MHz since the mindef isn't recalculated
for 5/10MHz like S1G. But then I'm not sure the S1G workaround for
ieee80211_sta_init_nss_bw_capa since maybe nss might be greater than
1 for 5/10MHz?

lachlan

[Johannes Berg]

Hi Lachlan,

On Mon, 2026-05-11 at 12:22 +1000, Lachlan Hodges wrote:
> > WARNING: ./include/net/mac80211.h:8114 at ieee80211_chan_width_to_rx_bw include/net/mac80211.h:8114 [inline], CPU#1: syz.4.4769/22510
> > WARNING: ./include/net/mac80211.h:8114 at ieee80211_sta_current_bw_tx_to_sta net/mac80211/sta_info.c:3719 [inline], CPU#1: syz.4.4769/22510
> > WARNING: ./include/net/mac80211.h:8114 at ieee80211_sta_current_bw+0x36d/0x510 net/mac80211/sta_info.c:3745, CPU#1: syz.4.4769/22510
> > Modules linked in:
> > CPU: 1 UID: 0 PID: 22510 Comm: syz.4.4769 Not tainted syzkaller #0 PREEMPT(full)
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
> > RIP: 0010:ieee80211_chan_width_to_rx_bw include/net/mac80211.h:8114 [inline]
> > RIP: 0010:ieee80211_sta_current_bw_tx_to_sta net/mac80211/sta_info.c:3719 [inline]
> > RIP: 0010:ieee80211_sta_current_bw+0x36d/0x510 net/mac80211/sta_info.c:3745
> > Code: 00 00 00 eb 49 41 83 fe 05 74 30 41 83 fe 0d 75 13 e8 47 8f af f6 b8 04 00 00 00 eb 31 e8 3b 8f af f6 eb 28 e8 34 8f af f6 90 <0f> 0b 90 eb 1d e8 29 8f af f6 b8 02 00 00 00 eb 13 e8 1d 8f af f6
> > RSP: 0018:ffffc90006f4eed8 EFLAGS: 00010283
> > RAX: ffffffff8b161cfc RBX: 1ffff1100d1da030 RCX: 0000000000080000
> > RDX: ffffc9000e5d2000 RSI: 0000000000000e31 RDI: 0000000000000e32
> > RBP: 0000000000000004 R08: ffff888054ad5c40 R09: 0000000000000007
> > R10: 000000000000000d R11: 0000000000000002 R12: ffff888068ed0180
> > R13: dffffc0000000000 R14: 0000000000000007 R15: 0000000000000000
> > FS: 00007fe58f5f66c0(0000) GS:ffff888125389000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 000000110c2c8823 CR3: 0000000038486000 CR4: 00000000003526f0
>
> This looks to be 10MHz given R14 = 7 which seems to be the operand
> being compared I think. The 2 patches I sent the other week should
> fix this occuring for any S1G bandwidths, not sure about 5 and 10MHz.

Thanks for taking a look at this! I'll apply those soon, seems the test
bot got stuck again.

> Atleast for this situation, it would be the same - we don't wanna
> recalc the mindef for 5 and 10MHz since the mindef isn't recalculated
> for 5/10MHz like S1G. But then I'm not sure the S1G workaround for
> ieee80211_sta_init_nss_bw_capa since maybe nss might be greater than
> 1 for 5/10MHz?

Technically, yes. However, 5/10 is pretty much unreachable in practice.
I had proposed removing it a long time ago, we should probably just do
that...

johannes