[v6.6] UBSAN: array-index-out-of-bounds in ieee80211_request_ibss_scan

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15f0450c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=898af5b35877fe1edd16
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bb8094930023/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6b695542f7a7/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f899d5f4fdd2/bzImage-6282921b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+898af5...@syzkaller.appspotmail.com

wlan1: Trigger new scan to find an IBSS to join
================================================================================
UBSAN: array-index-out-of-bounds in net/mac80211/scan.c:1209:5
index 1 is out of range for type 'struct ieee80211_channel *[] __counted_by(n_channels)' (aka 'struct ieee80211_channel *[]')
CPU: 0 PID: 6103 Comm: kworker/u4:13 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound cfg80211_wiphy_work
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
ubsan_epilogue+0xa/0x30 lib/ubsan.c:217
__ubsan_handle_out_of_bounds+0xe3/0xf0 lib/ubsan.c:348
ieee80211_request_ibss_scan+0x4eb/0x790 net/mac80211/scan.c:1209
ieee80211_sta_find_ibss net/mac80211/ibss.c:-1 [inline]
ieee80211_ibss_work+0xdfd/0x10c0 net/mac80211/ibss.c:1709
cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
================================================================================
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 1 PID: 6103 Comm: kworker/u4:13 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound cfg80211_wiphy_work
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
panic+0x2c0/0x710 kernel/panic.c:340
check_panic_on_warn+0x84/0xa0 kernel/panic.c:236
__ubsan_handle_out_of_bounds+0xe3/0xf0 lib/ubsan.c:348
ieee80211_request_ibss_scan+0x4eb/0x790 net/mac80211/scan.c:1209
ieee80211_sta_find_ibss net/mac80211/ibss.c:-1 [inline]
ieee80211_ibss_work+0xdfd/0x10c0 net/mac80211/ibss.c:1709
cfg80211_wiphy_work+0x225/0x260 net/wireless/core.c:437
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.