Message-ID: <689b0528.050a0220.51d73.00aa.GAE@google.com>
Date: Tue, 12 Aug 2025 02:11:04 -0700
From: syzbot <syzbot+30754ca335e6fb7e3092@...kaller.appspotmail.com>
To: dmantipov@...dex.ru, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [wireless?] KASAN: slab-use-after-free Read in cmp_bss

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in cmp_bss

==================================================================
BUG: KASAN: slab-use-after-free in cmp_bss+0xd4d/0xe80 net/wireless/scan.c:1504
Read of size 4 at addr ffff888000e6e898 by task kworker/u4:0/12

CPU: 0 UID: 0 PID: 12 Comm: kworker/u4:0 Not tainted 6.17.0-rc1-syzkaller-00004-g53e760d89498-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
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 cmp_bss+0xd4d/0xe80 net/wireless/scan.c:1504
 rb_find_bss net/wireless/scan.c:1693 [inline]
 __cfg80211_bss_update+0xd6/0x2140 net/wireless/scan.c:1982
 cfg80211_inform_single_bss_data+0xba9/0x1ac0 net/wireless/scan.c:2377
 cfg80211_inform_bss_data+0x1fb/0x3b30 net/wireless/scan.c:3236
 cfg80211_inform_bss_frame_data+0x3d7/0x730 net/wireless/scan.c:3327
 ieee80211_bss_info_update+0x746/0x9e0 net/mac80211/scan.c:226
 ieee80211_rx_bss_info+0x176/0x280 net/mac80211/mlme.c:6564
 ieee80211_rx_mgmt_probe_resp net/mac80211/mlme.c:6607 [inline]
 ieee80211_sta_rx_queued_mgmt+0x1294/0x4470 net/mac80211/mlme.c:8089
 ieee80211_iface_process_skb net/mac80211/iface.c:1696 [inline]
 ieee80211_iface_work+0x652/0x12d0 net/mac80211/iface.c:1753
 cfg80211_wiphy_work+0x2b8/0x470 net/wireless/core.c:435
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 3109:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4365 [inline]
 __kmalloc_noprof+0x27a/0x4f0 mm/slub.c:4377
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 cfg80211_inform_single_bss_data+0x905/0x1ac0 net/wireless/scan.c:2353
 cfg80211_inform_bss_data+0x1fb/0x3b30 net/wireless/scan.c:3236
 cfg80211_inform_bss_frame_data+0x3d7/0x730 net/wireless/scan.c:3327
 ieee80211_bss_info_update+0x746/0x9e0 net/mac80211/scan.c:226
 ieee80211_rx_bss_info+0x176/0x280 net/mac80211/mlme.c:6564
 ieee80211_rx_mgmt_beacon+0x197d/0x2cd0 net/mac80211/mlme.c:7513
 ieee80211_sta_rx_queued_mgmt+0x4ed/0x4470 net/mac80211/mlme.c:8085
 ieee80211_iface_process_skb net/mac80211/iface.c:1696 [inline]
 ieee80211_iface_work+0x652/0x12d0 net/mac80211/iface.c:1753
 cfg80211_wiphy_work+0x2b8/0x470 net/wireless/core.c:435
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 3109:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free_freelist_hook mm/slub.c:2446 [inline]
 slab_free_bulk mm/slub.c:4704 [inline]
 kmem_cache_free_bulk+0x2d1/0x520 mm/slub.c:5283
 kfree_bulk include/linux/slab.h:794 [inline]
 kvfree_rcu_bulk+0xe5/0x1f0 mm/slab_common.c:1516
 kvfree_rcu_drain_ready mm/slab_common.c:1699 [inline]
 kfree_rcu_monitor+0x211/0x2a0 mm/slab_common.c:1772
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548
 kvfree_call_rcu+0xbb/0x410 mm/slab_common.c:1962
 cfg80211_update_known_bss+0x9e8/0x13d0 net/wireless/scan.c:1921
 cfg80211_update_assoc_bss_entry+0x4ba/0x6a0 net/wireless/scan.c:3456
 cfg80211_ch_switch_notify+0x3c1/0x780 net/wireless/nl80211.c:20398
 ieee80211_sta_process_chanswitch+0xad4/0x2870 net/mac80211/mlme.c:-1
 ieee80211_rx_mgmt_beacon+0x19c7/0x2cd0 net/mac80211/mlme.c:7515
 ieee80211_sta_rx_queued_mgmt+0x4ed/0x4470 net/mac80211/mlme.c:8085
 ieee80211_iface_process_skb net/mac80211/iface.c:1696 [inline]
 ieee80211_iface_work+0x652/0x12d0 net/mac80211/iface.c:1753
 cfg80211_wiphy_work+0x2b8/0x470 net/wireless/core.c:435
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888000e6e880
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 24 bytes inside of
 freed 96-byte region [ffff888000e6e880, ffff888000e6e8e0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xe6e
flags: 0x7ff00000000000(node=0|zone=0|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 007ff00000000000 ffff88801a441280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000200020 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x252800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_THISNODE), pid 3109, tgid 3109 (kworker/u4:11), ts 107292613223, free_ts 31900007900
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_slab_page mm/slub.c:2489 [inline]
 allocate_slab+0x65/0x370 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 __do_kmalloc_node mm/slub.c:4364 [inline]
 __kmalloc_node_noprof+0x2fd/0x4e0 mm/slub.c:4371
 kmalloc_array_node_noprof include/linux/slab.h:1020 [inline]
 alloc_slab_obj_exts mm/slub.c:2028 [inline]
 account_slab mm/slub.c:2614 [inline]
 allocate_slab+0x16a/0x370 mm/slub.c:2674
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4236
 dst_alloc+0x105/0x170 net/core/dst.c:89
 ip6_dst_alloc net/ipv6/route.c:342 [inline]
 icmp6_dst_alloc+0x75/0x420 net/ipv6/route.c:3324
 mld_sendpack+0x678/0xd80 net/ipv6/mcast.c:1849
 ipv6_mc_dad_complete+0x88/0x410 net/ipv6/mcast.c:2284
 addrconf_dad_completed+0x6d5/0xd60 net/ipv6/addrconf.c:4340
 addrconf_dad_work+0xc36/0x14b0 net/ipv6/addrconf.c:-1
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
page last free pid 4756 tgid 4756 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Memory state around the buggy address:
 ffff888000e6e780: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff888000e6e800: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
>ffff888000e6e880: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                            ^
 ffff888000e6e900: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888000e6e980: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


Tested on:

commit:         53e760d8 Merge tag 'nfsd-6.17-1' of git://git.kernel.o..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10c54af0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d67d3af29f50297e
dashboard link: https://syzkaller.appspot.com/bug?extid=30754ca335e6fb7e3092
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15ffe5a2580000

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