[moderation] [bluetooth?] KASAN: slab-use-after-free Read in force_suspend_read (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d561baae505 Merge tag 'x86_urgent_for_v6.17_rc2' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=101106f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4a59f5ce3f5878f0
dashboard link: https://syzkaller.appspot.com/bug?extid=aaab2496817184be60b5
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-b...@vger.kernel.org linux-...@vger.kernel.org luiz....@gmail.com mar...@holtmann.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3c8e63656e52/disk-8d561baa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/19f4251b8bfd/vmlinux-8d561baa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aca2c5602160/bzImage-8d561baa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aaab24...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in force_suspend_read+0x12c/0x140 drivers/bluetooth/hci_vhci.c:118
Read of size 1 at addr ffff888032c45a30 by task syz.2.3442/30492

CPU: 1 UID: 0 PID: 30492 Comm: syz.2.3442 Tainted: G U 6.17.0-rc1-syzkaller-00224-g8d561baae505 #0 PREEMPT(full)
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcd/0x630 mm/kasan/report.c:482
kasan_report+0xe0/0x110 mm/kasan/report.c:595
force_suspend_read+0x12c/0x140 drivers/bluetooth/hci_vhci.c:118
full_proxy_read+0x12e/0x1a0 fs/debugfs/file.c:378
vfs_read+0x1e1/0xcf0 fs/read_write.c:570
ksys_read+0x12a/0x250 fs/read_write.c:715
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3dbff8ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3dc0de9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f3dc01b5fa0 RCX: 00007f3dbff8ebe9
RDX: 0000000000000084 RSI: 00002000000005c0 RDI: 0000000000000004
RBP: 00007f3dc0011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3dc01b6038 R14: 00007f3dc01b5fa0 R15: 00007ffdec3da008
</TASK>

Allocated by task 16068:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
vhci_open+0x4c/0x430 drivers/bluetooth/hci_vhci.c:635
misc_open+0x35a/0x420 drivers/char/misc.c:161
chrdev_open+0x234/0x6a0 fs/char_dev.c:414
do_dentry_open+0x982/0x1530 fs/open.c:965
vfs_open+0x82/0x3f0 fs/open.c:1095
do_open fs/namei.c:3887 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4046
do_filp_open+0x20b/0x470 fs/namei.c:4073
do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
do_sys_open fs/open.c:1450 [inline]
__do_sys_openat fs/open.c:1466 [inline]
__se_sys_openat fs/open.c:1461 [inline]
__x64_sys_openat+0x174/0x210 fs/open.c:1461
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 18166:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:243 [inline]
__kasan_slab_free+0x60/0x70 mm/kasan/common.c:275
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2417 [inline]
slab_free mm/slub.c:4680 [inline]
kfree+0x2b4/0x4d0 mm/slub.c:4879
vhci_release+0xbb/0xf0 drivers/bluetooth/hci_vhci.c:671
__fput+0x402/0xb70 fs/file_table.c:468
task_work_run+0x150/0x240 kernel/task_work.c:227
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x86f/0x2bf0 kernel/exit.c:961
do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
get_signal+0x2673/0x26d0 kernel/signal.c:3034
arch_do_signal_or_restart+0x8f/0x790 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x84/0x110 kernel/entry/common.c:40
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x3f6/0x490 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888032c45800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 560 bytes inside of
freed 1024-byte region [ffff888032c45800, ffff888032c45c00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32c40
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b841dc0 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b841dc0 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000cb1001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 11469, tgid 11464 (syz.0.1096), ts 310535457920, free_ts 310133313338
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
prep_new_page mm/page_alloc.c:1859 [inline]
get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
__alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
alloc_slab_page mm/slub.c:2487 [inline]
allocate_slab mm/slub.c:2655 [inline]
new_slab+0x247/0x330 mm/slub.c:2709
___slab_alloc+0xcf2/0x1740 mm/slub.c:3891
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3981
__slab_alloc_node mm/slub.c:4056 [inline]
slab_alloc_node mm/slub.c:4217 [inline]
__kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4391
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
afs_alloc_call+0x51/0x640 fs/afs/rxrpc.c:163
afs_charge_preallocation+0xf7/0x320 fs/afs/rxrpc.c:747
afs_open_socket+0x323/0x400 fs/afs/rxrpc.c:112
afs_net_init+0x825/0xb00 fs/afs/main.c:116
ops_init+0x1df/0x5f0 net/core/net_namespace.c:136
setup_net+0x10f/0x380 net/core/net_namespace.c:438
copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:570
create_new_namespaces+0x3ea/0xa90 kernel/nsproxy.c:110
page last free pid 11446 tgid 11435 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1395 [inline]
__free_frozen_pages+0x7d5/0x10f0 mm/page_alloc.c:2895
discard_slab mm/slub.c:2753 [inline]
__put_partials+0x165/0x1c0 mm/slub.c:3218
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:340
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4180 [inline]
slab_alloc_node mm/slub.c:4229 [inline]
kmem_cache_alloc_node_noprof+0x1d5/0x3b0 mm/slub.c:4281
__alloc_skb+0x2b2/0x380 net/core/skbuff.c:659
alloc_skb_fclone include/linux/skbuff.h:1386 [inline]
tipc_buf_acquire+0x26/0xe0 net/tipc/msg.c:72
tipc_msg_build+0x112/0x1150 net/tipc/msg.c:390
__tipc_sendmsg+0xa30/0x19a0 net/tipc/socket.c:1501
tipc_sendmsg+0x4f/0x70 net/tipc/socket.c:1399
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg net/socket.c:729 [inline]
____sys_sendmsg+0xa95/0xc70 net/socket.c:2614
___sys_sendmsg+0x134/0x1d0 net/socket.c:2668
__sys_sendmmsg+0x200/0x420 net/socket.c:2757
__do_sys_sendmmsg net/socket.c:2784 [inline]
__se_sys_sendmmsg net/socket.c:2781 [inline]
__x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2781
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94

Memory state around the buggy address:
ffff888032c45900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888032c45980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888032c45a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888032c45a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888032c45b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

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