[moderation] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_disconn_ind (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aaf724ed6926 Merge tag 'v6.16-rc3-smb3-client-fixes' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1295088c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=641bc01f4fbdccd4
dashboard link: https://syzkaller.appspot.com/bug?extid=e2cdb2b21673433bfa75
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [johan....@gmail.com 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/7210817f9bfd/disk-aaf724ed.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9f1f603af108/vmlinux-aaf724ed.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c2fffbee128/bzImage-aaf724ed.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e2cdb2...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in l2cap_disconn_ind+0xbc/0xd0 net/bluetooth/l2cap_core.c:7299
Read of size 1 at addr ffff88807807bab0 by task kworker/u9:5/5827

CPU: 1 UID: 0 PID: 5827 Comm: kworker/u9:5 Not tainted 6.16.0-rc3-syzkaller-00306-gaaf724ed6926 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: hci1 hci_conn_timeout
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:408 [inline]
print_report+0xcd/0x680 mm/kasan/report.c:521
kasan_report+0xe0/0x110 mm/kasan/report.c:634
l2cap_disconn_ind+0xbc/0xd0 net/bluetooth/l2cap_core.c:7299
hci_proto_disconn_ind include/net/bluetooth/hci_core.h:2032 [inline]
hci_conn_timeout+0x190/0x210 net/bluetooth/hci_conn.c:580
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3321 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

Allocated by task 26062:
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:377 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
l2cap_conn_add.part.0+0x60/0xa60 net/bluetooth/l2cap_core.c:6870
l2cap_conn_add include/net/bluetooth/hci_core.h:1638 [inline]
l2cap_chan_connect+0x15e5/0x2020 net/bluetooth/l2cap_core.c:7061
bt_6lowpan_connect net/bluetooth/6lowpan.c:900 [inline]
lowpan_control_write+0x3c9/0x740 net/bluetooth/6lowpan.c:1135
full_proxy_write+0x13c/0x200 fs/debugfs/file.c:398
vfs_write+0x2a0/0x1150 fs/read_write.c:684
ksys_write+0x12a/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 26076:
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:247 [inline]
__kasan_slab_free+0x51/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2381 [inline]
slab_free mm/slub.c:4643 [inline]
kfree+0x2b4/0x4d0 mm/slub.c:4842
l2cap_conn_free net/bluetooth/l2cap_core.c:1811 [inline]
kref_put include/linux/kref.h:65 [inline]
l2cap_conn_put net/bluetooth/l2cap_core.c:1823 [inline]
l2cap_conn_del+0x59c/0x730 net/bluetooth/l2cap_core.c:1803
l2cap_connect_cfm+0x9e1/0xf80 net/bluetooth/l2cap_core.c:7243
hci_connect_cfm include/net/bluetooth/hci_core.h:2056 [inline]
hci_conn_failed+0x1ba/0x330 net/bluetooth/hci_conn.c:1275
hci_abort_conn_sync+0x762/0xb10 net/bluetooth/hci_sync.c:5645
hci_disconnect_all_sync.constprop.0+0x104/0x3c0 net/bluetooth/hci_sync.c:5668
hci_suspend_sync+0x770/0xab0 net/bluetooth/hci_sync.c:6145
hci_suspend_dev+0x308/0x500 net/bluetooth/hci_core.c:2851
hci_suspend_notifier+0x28d/0x2f0 net/bluetooth/hci_core.c:2422
notifier_call_chain+0xb9/0x410 kernel/notifier.c:85
notifier_call_chain_robust kernel/notifier.c:120 [inline]
blocking_notifier_call_chain_robust kernel/notifier.c:345 [inline]
blocking_notifier_call_chain_robust+0xc8/0x160 kernel/notifier.c:333
pm_notifier_call_chain_robust+0x27/0x60 kernel/power/main.c:102
snapshot_open+0x189/0x2b0 kernel/power/user.c:77
misc_open+0x35a/0x420 drivers/char/misc.c:161
chrdev_open+0x234/0x6a0 fs/char_dev.c:414
do_dentry_open+0x744/0x1c10 fs/open.c:964
vfs_open+0x82/0x3f0 fs/open.c:1094
do_open fs/namei.c:3896 [inline]
path_openat+0x1de4/0x2cb0 fs/namei.c:4055
do_filp_open+0x20b/0x470 fs/namei.c:4082
do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88807807b800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 688 bytes inside of
freed 1024-byte region [ffff88807807b800, ffff88807807bc00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x78078
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 ffffea0001e01e01 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 5718, tgid 5718 (dhcpcd-run-hook), ts 50410375153, free_ts 50186621838
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959
alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2451 [inline]
allocate_slab mm/slub.c:2619 [inline]
new_slab+0x23b/0x330 mm/slub.c:2673
___slab_alloc+0xd9c/0x1940 mm/slub.c:3859
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949
__slab_alloc_node mm/slub.c:4024 [inline]
slab_alloc_node mm/slub.c:4185 [inline]
__do_kmalloc_node mm/slub.c:4327 [inline]
__kmalloc_noprof+0x2f2/0x510 mm/slub.c:4340
kmalloc_noprof include/linux/slab.h:909 [inline]
load_elf_phdrs+0x102/0x210 fs/binfmt_elf.c:525
load_elf_binary+0x1fa/0x4f00 fs/binfmt_elf.c:854
search_binary_handler fs/exec.c:1665 [inline]
exec_binprm fs/exec.c:1697 [inline]
bprm_execve fs/exec.c:1749 [inline]
bprm_execve+0x8c0/0x1650 fs/exec.c:1725
do_execveat_common.isra.0+0x4a5/0x610 fs/exec.c:1855
do_execve fs/exec.c:1929 [inline]
__do_sys_execve fs/exec.c:2005 [inline]
__se_sys_execve fs/exec.c:2000 [inline]
__x64_sys_execve+0x8e/0xb0 fs/exec.c:2000
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5704 tgid 5704 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0x7fe/0x1180 mm/page_alloc.c:2706
discard_slab mm/slub.c:2717 [inline]
__put_partials+0x16d/0x1c0 mm/slub.c:3186
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:329
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4148 [inline]
slab_alloc_node mm/slub.c:4197 [inline]
kmem_cache_alloc_noprof+0x1cb/0x3b0 mm/slub.c:4204
getname_flags.part.0+0x4c/0x550 fs/namei.c:146
getname_flags+0x93/0xf0 include/linux/audit.h:322
getname include/linux/fs.h:2907 [inline]
do_sys_openat2+0xb8/0x1d0 fs/open.c:1431
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x174/0x210 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88807807b980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807807ba00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807807ba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807807bb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807807bb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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