Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in mgmt_remove_adv_monitor_complete (3)

syzbot
2025-06-02T18:23:02Z

Hello,

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

Bluetooth: hci0: unexpected cc 0x0c23 length: 249 > 4
Bluetooth: hci0: unexpected cc 0x0c38 length: 249 > 2
==================================================================
BUG: KASAN: slab-use-after-free in mgmt_remove_adv_monitor_complete+0xe5/0x5a0 net/bluetooth/mgmt.c:5399
Read of size 8 at addr ffff8880115a3aa0 by task kworker/u5:4/5846

CPU: 0 UID: 0 PID: 5846 Comm: kworker/u5:4 Not tainted 6.15.0-syzkaller-gcd2e103d57e5-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: hci0 hci_cmd_sync_work
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xd2/0x2b0 mm/kasan/report.c:521
kasan_report+0x118/0x150 mm/kasan/report.c:634
mgmt_remove_adv_monitor_complete+0xe5/0x5a0 net/bluetooth/mgmt.c:5399
hci_cmd_sync_work+0x261/0x3a0 net/bluetooth/hci_sync.c:334
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

Allocated by task 13316:
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:377 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4358
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
mgmt_pending_new+0x65/0x1e0 net/bluetooth/mgmt_util.c:269
mgmt_pending_add+0x35/0x140 net/bluetooth/mgmt_util.c:296
remove_adv_monitor+0x103/0x1b0 net/bluetooth/mgmt.c:5447
hci_mgmt_cmd+0x9c9/0xef0 net/bluetooth/hci_sock.c:1719
hci_sock_sendmsg+0x6ca/0xef0 net/bluetooth/hci_sock.c:1839
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x219/0x270 net/socket.c:727
sock_write_iter+0x258/0x330 net/socket.c:1131
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x54b/0xa90 fs/read_write.c:686
ksys_write+0x145/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 13322:
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:247 [inline]
__kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2380 [inline]
slab_free mm/slub.c:4642 [inline]
kfree+0x18e/0x440 mm/slub.c:4841
mgmt_pending_free net/bluetooth/mgmt_util.c:311 [inline]
mgmt_pending_foreach+0x30d/0x380 net/bluetooth/mgmt_util.c:257
mgmt_index_removed+0x112/0x2f0 net/bluetooth/mgmt.c:9359
hci_sock_bind+0xbe9/0x1000 net/bluetooth/hci_sock.c:1314
__sys_bind_socket net/socket.c:1810 [inline]
__sys_bind+0x2c6/0x3e0 net/socket.c:1841
__do_sys_bind net/socket.c:1846 [inline]
__se_sys_bind net/socket.c:1844 [inline]
__x64_sys_bind+0x7a/0x90 net/socket.c:1844
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880115a3a80
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 32 bytes inside of
freed 96-byte region [ffff8880115a3a80, ffff8880115a3ae0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x115a3
ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801a441280 ffffea0000681b00 dead000000000003
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 5851, tgid 5851 (syz-executor), ts 158761816277, free_ts 158220175343
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
__alloc_pages_slowpath+0x2fe/0xce0 mm/page_alloc.c:4490
__alloc_frozen_pages_noprof+0x319/0x370 mm/page_alloc.c:4972
alloc_slab_page mm/slub.c:2452 [inline]
allocate_slab+0x65/0x3b0 mm/slub.c:2618
new_slab mm/slub.c:2672 [inline]
___slab_alloc+0xbfc/0x1480 mm/slub.c:3858
__slab_alloc mm/slub.c:3948 [inline]
__slab_alloc_node mm/slub.c:4023 [inline]
slab_alloc_node mm/slub.c:4184 [inline]
__kmalloc_cache_node_noprof+0x29a/0x3d0 mm/slub.c:4366
kmalloc_node_noprof include/linux/slab.h:928 [inline]
alloc_node_nr_active kernel/workqueue.c:4874 [inline]
__alloc_workqueue+0x6a4/0x1b70 kernel/workqueue.c:5728
alloc_workqueue+0xd4/0x210 kernel/workqueue.c:5788
ieee80211_register_hw+0x2c5f/0x4120 net/mac80211/main.c:1491
mac80211_hwsim_new_radio+0x2f0e/0x5340 drivers/net/wireless/virtual/mac80211_hwsim.c:5565
hwsim_new_radio_nl+0xea4/0x1b10 drivers/net/wireless/virtual/mac80211_hwsim.c:6249
genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2534
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
page last free pid 5977 tgid 5977 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
vfree+0x25a/0x400 mm/vmalloc.c:3426
delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3345
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
ffff8880115a3980: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8880115a3a00: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
>ffff8880115a3a80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff8880115a3b00: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
ffff8880115a3b80: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
==================================================================

Tested on:

commit: cd2e103d Merge tag 'hardening-v6.16-rc1-fix1-take2' of..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1032ac82580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6acfdd5e5c8ef3d0
dashboard link: https://syzkaller.appspot.com/bug?extid=feb0dc579bbe30a13190
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch: https://syzkaller.appspot.com/x/patch.diff?x=1182ac82580000