[syzbot ci] Re: net: cfg80211: Validate monitor channel set against radio usage

[syzbot ci <syzbot+ci5ae471ec6c7a1072@syzkaller.appspotmail.com>]

syzbot ci has tested the following series

[v1] net: cfg80211: Validate monitor channel set against radio usage
https://lore.kernel.org/all/20260917221205.3214125-1-roryl@candelatech.com
* [PATCH wireless-next] net: cfg80211: Validate monitor channel set against radio usage

and found the following issue:
UBSAN: shift-out-of-bounds in cfg80211_set_monitor_channel

Full report is available here:
https://ci.syzbot.org/series/096ed229-0401-4402-9865-92c5b6d81b57

***

UBSAN: shift-out-of-bounds in cfg80211_set_monitor_channel

tree:      wireless-next
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/wireless/wireless-next.git
base:      3b35f726c20d138fafa154182ee926a419306269
arch:      amd64
compiler:  Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
config:    https://ci.syzbot.org/builds/7147a923-683e-41dc-b623-05cfe4ac2a30/config
syz repro: https://ci.syzbot.org/findings/525583ec-5ed7-4adc-aeab-6eb3b293f9ee/syz_repro

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in net/wireless/chan.c:1831:49
shift exponent -22 is negative
CPU: 1 UID: 0 PID: 5855 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x36d/0x400 lib/ubsan.c:494
 cfg80211_can_set_monitor_channel net/wireless/chan.c:1831 [inline]
 cfg80211_set_monitor_channel+0x38a/0x8d0 net/wireless/chan.c:1844
 __nl80211_set_channel+0x340/0x990 net/wireless/nl80211.c:4203
 nl80211_set_wiphy+0x127c/0x3050 net/wireless/nl80211.c:-1
 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2713
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
 __sys_sendmsg net/socket.c:2799 [inline]
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2802
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7e3a59e159
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:00007f7e3b3d5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7e3a825fa0 RCX: 00007f7e3a59e159
RDX: 0000000004040000 RSI: 0000200000000040 RDI: 0000000000000003
RBP: 00007f7e3a63506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7e3a826038 R14: 00007f7e3a825fa0 R15: 00007ffd12ef16a8
 </TASK>
---[ end trace ]---


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@syzkaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.

To test a fix for this bug, please reply with `#syz test`
(on a separate line) and attach the patch to the email.

Notes:
- The patch will be applied on top of the tested series (as an
  incremental fix).
- To test a new version of the whole series, please send it directly
  to syzbot@lists.linux.dev.
- Arguments like custom git repos and branches are not supported.