Re: [syzbot] [wireless?] UBSAN: array-index-out-of-bounds in ieee80211_request_ibss_scan

[syzbot <syzbot+4bcdddd48bb6f0be0da1@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: array-index-out-of-bounds in ieee80211_request_ibss_scan

wlan1: Trigger new scan to find an IBSS to join
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in net/mac80211/scan.c:1208:5
index 0 is out of range for type 'struct ieee80211_channel *[] __counted_by(n_channels)' (aka 'struct ieee80211_channel *[]')
CPU: 0 UID: 0 PID: 1038 Comm: kworker/u4:7 Not tainted 6.15.0-rc4-syzkaller-gca91b9500108-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound cfg80211_wiphy_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:231
 __ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:453
 ieee80211_request_ibss_scan+0x600/0x8b0 net/mac80211/scan.c:1208
 ieee80211_sta_find_ibss net/mac80211/ibss.c:-1 [inline]
 ieee80211_ibss_work+0xde7/0x1060 net/mac80211/ibss.c:1670
 cfg80211_wiphy_work+0x2dc/0x460 net/wireless/core.c:435
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
---[ end trace ]---
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 0 UID: 0 PID: 1038 Comm: kworker/u4:7 Not tainted 6.15.0-rc4-syzkaller-gca91b9500108-dirty #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound cfg80211_wiphy_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x99/0x250 lib/dump_stack.c:120
 panic+0x2db/0x790 kernel/panic.c:354
 check_panic_on_warn+0x89/0xb0 kernel/panic.c:243
 __ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:453
 ieee80211_request_ibss_scan+0x600/0x8b0 net/mac80211/scan.c:1208
 ieee80211_sta_find_ibss net/mac80211/ibss.c:-1 [inline]
 ieee80211_ibss_work+0xde7/0x1060 net/mac80211/ibss.c:1670
 cfg80211_wiphy_work+0x2dc/0x460 net/wireless/core.c:435
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..


Tested on:

commit:         ca91b950 Merge tag 'v6.15-rc4-ksmbd-server-fixes' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12847374580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=714654674710be70
dashboard link: https://syzkaller.appspot.com/bug?extid=4bcdddd48bb6f0be0da1
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10911374580000