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

syzbot
2025-05-14T04:27:31Z

Hello,

syzbot found the following issue on:

HEAD commit: ea34704d6ad7 Merge tag 'drm-fixes-2025-05-10' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1663acf4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=91c351a0f6229e67
dashboard link: https://syzkaller.appspot.com/bug?extid=feb0dc579bbe30a13190
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=112c9768580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1526e670580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ea34704d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c7e586f1a091/vmlinux-ea34704d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cd61ffd40938/bzImage-ea34704d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+feb0dc579bbe30a13190@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in mgmt_remove_adv_monitor_complete+0xe5/0x540 net/bluetooth/mgmt.c:5405
Read of size 8 at addr ffff888048891a18 by task kworker/u5:8/5333

CPU: 0 UID: 0 PID: 5333 Comm: kworker/u5:8 Not tainted 6.15.0-rc5-syzkaller-00197-gea34704d6ad7 #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+0xb4/0x290 mm/kasan/report.c:521
kasan_report+0x118/0x150 mm/kasan/report.c:634
mgmt_remove_adv_monitor_complete+0xe5/0x540 net/bluetooth/mgmt.c:5405
hci_cmd_sync_work+0x25e/0x3a0 net/bluetooth/hci_sync.c:334
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>

Allocated by task 5702:
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+0x65/0x240 net/bluetooth/mgmt_util.c:252
mgmt_pending_add+0x34/0x120 net/bluetooth/mgmt_util.c:279
remove_adv_monitor+0x103/0x1b0 net/bluetooth/mgmt.c:5453
hci_mgmt_cmd+0x9c6/0xef0 net/bluetooth/hci_sock.c:1712
hci_sock_sendmsg+0x6ca/0xee0 net/bluetooth/hci_sock.c:1832
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:591 [inline]
vfs_write+0x548/0xa90 fs/read_write.c:684
ksys_write+0x145/0x250 fs/read_write.c:736
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5700:
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+0x193/0x440 mm/slub.c:4841
mgmt_pending_foreach+0xc9/0x120 net/bluetooth/mgmt_util.c:242
mgmt_index_removed+0x10d/0x2f0 net/bluetooth/mgmt.c:9362
hci_sock_bind+0xbe9/0x1000 net/bluetooth/hci_sock.c:1307
__sys_bind_socket net/socket.c:1810 [inline]
__sys_bind+0x2c3/0x3e0 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+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888048891a00
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 24 bytes inside of
freed 96-byte region [ffff888048891a00, ffff888048891a60)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x48891
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000000 ffff88801a041280 ffffea0000d6e3c0 dead000000000008
raw: 0000000000000000 0000000080200020 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 5317, tgid 5317 (syz-executor420), ts 80512529929, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1d8/0x230 mm/page_alloc.c:1718
prep_new_page mm/page_alloc.c:1726 [inline]
get_page_from_freelist+0x21ce/0x22b0 mm/page_alloc.c:3688
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4970
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:4872 [inline]
__alloc_workqueue+0x6a4/0x1b70 kernel/workqueue.c:5726
alloc_workqueue+0xd4/0x210 kernel/workqueue.c:5786
tipc_topsrv_work_start net/tipc/topsrv.c:635 [inline]
tipc_topsrv_start net/tipc/topsrv.c:679 [inline]
tipc_topsrv_init_net+0x37f/0x830 net/tipc/topsrv.c:725
ops_init+0x359/0x5c0 net/core/net_namespace.c:138
setup_net+0x238/0x830 net/core/net_namespace.c:364
copy_net_ns+0x32e/0x590 net/core/net_namespace.c:518
create_new_namespaces+0x3d3/0x700 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:228
ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3375
__do_sys_unshare kernel/fork.c:3446 [inline]
__se_sys_unshare kernel/fork.c:3444 [inline]
__x64_sys_unshare+0x38/0x50 kernel/fork.c:3444
page_owner free stack trace missing

Memory state around the buggy address:
ffff888048891900: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888048891980: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff888048891a00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff888048891a80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888048891b00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================

---
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