[v6.1] KASAN: use-after-free Read in l2cap_sock_new_connection_cb

Hello,

syzbot found the following issue on:

HEAD commit: 7c15117f9468 Linux 6.1.115
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17c86187980000
kernel config: https://syzkaller.appspot.com/x/.config?x=8b63260ee6ff0e8a
dashboard link: https://syzkaller.appspot.com/bug?extid=2ee072e03ed03586a60e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3a088ae26c9b/disk-7c15117f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3c714c0976a2/vmlinux-7c15117f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1e6e2840ff4a/bzImage-7c15117f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

Bluetooth: hci3: failed to register connection device
==================================================================
BUG: KASAN: use-after-free in l2cap_sock_new_connection_cb+0x1ef/0x2a0 net/bluetooth/l2cap_sock.c:1517
Read of size 8 at addr ffff88802ff52540 by task kworker/u5:5/4262

CPU: 0 PID: 4262 Comm: kworker/u5:5 Not tainted 6.1.115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: hci3 hci_rx_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
print_address_description mm/kasan/report.c:284 [inline]
print_report+0x15f/0x4f0 mm/kasan/report.c:395
kasan_report+0x136/0x160 mm/kasan/report.c:495
l2cap_sock_new_connection_cb+0x1ef/0x2a0 net/bluetooth/l2cap_sock.c:1517
l2cap_connect_cfm+0x36b/0x1270 net/bluetooth/l2cap_core.c:8326
hci_connect_cfm+0x9e/0x150 include/net/bluetooth/hci_core.h:1788
le_conn_complete_evt+0xd54/0x1320 net/bluetooth/hci_event.c:6008
hci_le_conn_complete_evt+0x188/0x410 net/bluetooth/hci_event.c:6034
hci_event_func net/bluetooth/hci_event.c:7533 [inline]
hci_event_packet+0xa40/0x1510 net/bluetooth/hci_event.c:7588
hci_rx_work+0x3cd/0xce0 net/bluetooth/hci_core.c:4100
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

Allocated by task 4262:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slab_common.c:936 [inline]
__kmalloc+0xb2/0x230 mm/slab_common.c:949
kmalloc include/linux/slab.h:562 [inline]
sk_prot_alloc+0xe0/0x200 net/core/sock.c:2047
sk_alloc+0x36/0x350 net/core/sock.c:2100
bt_sock_alloc+0x37/0x130 net/bluetooth/af_bluetooth.c:148
l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1911 [inline]
l2cap_sock_new_connection_cb+0xd8/0x2a0 net/bluetooth/l2cap_sock.c:1502
l2cap_connect_cfm+0x36b/0x1270 net/bluetooth/l2cap_core.c:8326
hci_connect_cfm+0x9e/0x150 include/net/bluetooth/hci_core.h:1788
le_conn_complete_evt+0xd54/0x1320 net/bluetooth/hci_event.c:6008
hci_le_conn_complete_evt+0x188/0x410 net/bluetooth/hci_event.c:6034
hci_event_func net/bluetooth/hci_event.c:7533 [inline]
hci_event_packet+0xa40/0x1510 net/bluetooth/hci_event.c:7588
hci_rx_work+0x3cd/0xce0 net/bluetooth/hci_core.c:4100
process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
kthread+0x28d/0x320 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 6616:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook mm/slub.c:1750 [inline]
slab_free mm/slub.c:3661 [inline]
__kmem_cache_free+0x25c/0x3c0 mm/slub.c:3674
sk_prot_free net/core/sock.c:2083 [inline]
__sk_destruct+0x473/0x5f0 net/core/sock.c:2169
l2cap_sock_cleanup_listen+0xd9/0x270 net/bluetooth/l2cap_sock.c:1482
l2cap_sock_release+0x59/0x1d0 net/bluetooth/l2cap_sock.c:1445
__sock_release net/socket.c:654 [inline]
sock_close+0xcd/0x230 net/socket.c:1400
__fput+0x3f6/0x8d0 fs/file_table.c:320
task_work_run+0x246/0x300 kernel/task_work.c:203
get_signal+0x15fc/0x17d0 kernel/signal.c:2647
arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871
exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
kasan_save_stack+0x3b/0x60 mm/kasan/common.c:45
__kasan_record_aux_stack+0xb0/0xc0 mm/kasan/generic.c:486
call_rcu+0x163/0xa10 kernel/rcu/tree.c:2845
netlink_release+0x1554/0x19e0 net/netlink/af_netlink.c:815
__sock_release net/socket.c:654 [inline]
sock_close+0xcd/0x230 net/socket.c:1400
__fput+0x3f6/0x8d0 fs/file_table.c:320
task_work_run+0x246/0x300 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:177
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88802ff52000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1344 bytes inside of
2048-byte region [ffff88802ff52000, ffff88802ff52800)

The buggy address belongs to the physical page:
page:ffffea0000bfd400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2ff50
head:ffffea0000bfd400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888017c42000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4247, tgid 4247 (syz-executor), ts 70462366767, free_ts 69102608260
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2517
prep_new_page mm/page_alloc.c:2524 [inline]
get_page_from_freelist+0x322e/0x33b0 mm/page_alloc.c:4290
__alloc_pages+0x28d/0x770 mm/page_alloc.c:5558
alloc_slab_page+0x6a/0x150 mm/slub.c:1794
allocate_slab mm/slub.c:1939 [inline]
new_slab+0x84/0x2d0 mm/slub.c:1992
___slab_alloc+0xc20/0x1270 mm/slub.c:3180
__slab_alloc mm/slub.c:3279 [inline]
slab_alloc_node mm/slub.c:3364 [inline]
__kmem_cache_alloc_node+0x19f/0x260 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:935 [inline]
__kmalloc_node_track_caller+0xa0/0x220 mm/slab_common.c:956
kmalloc_reserve net/core/skbuff.c:446 [inline]
__alloc_skb+0x135/0x670 net/core/skbuff.c:515
alloc_skb include/linux/skbuff.h:1271 [inline]
nlmsg_new include/net/netlink.h:991 [inline]
rtmsg_ifinfo_build_skb+0x81/0x180 net/core/rtnetlink.c:3963
rtmsg_ifinfo_event net/core/rtnetlink.c:3999 [inline]
rtmsg_ifinfo+0x71/0x120 net/core/rtnetlink.c:4008
__dev_notify_flags+0xdd/0x610 net/core/dev.c:8623
dev_change_flags+0xe7/0x190 net/core/dev.c:8665
do_setlink+0xcf4/0x3de0 net/core/rtnetlink.c:2830
__rtnl_newlink net/core/rtnetlink.c:3605 [inline]
rtnl_newlink+0x172c/0x2050 net/core/rtnetlink.c:3652
rtnetlink_rcv_msg+0x818/0xff0 net/core/rtnetlink.c:6150
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1444 [inline]
free_pcp_prepare mm/page_alloc.c:1494 [inline]
free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3369
free_unref_page+0x33/0x3e0 mm/page_alloc.c:3464
__skb_frag_unref include/linux/skbuff.h:3436 [inline]
skb_release_data+0x37f/0x7a0 net/core/skbuff.c:785
skb_release_all net/core/skbuff.c:856 [inline]
__kfree_skb+0x4c/0x60 net/core/skbuff.c:870
tcp_clean_rtx_queue net/ipv4/tcp_input.c:3400 [inline]
tcp_ack+0x246c/0x6e80 net/ipv4/tcp_input.c:3959
tcp_rcv_established+0xf53/0x1f00 net/ipv4/tcp_input.c:6006
tcp_v4_do_rcv+0x487/0xb00 net/ipv4/tcp_ipv4.c:1683
sk_backlog_rcv include/net/sock.h:1119 [inline]
__release_sock+0x198/0x4b0 net/core/sock.c:2936
release_sock+0x5d/0x1c0 net/core/sock.c:3500
tcp_sendmsg+0x36/0x40 net/ipv4/tcp.c:1491
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
sock_write_iter+0x394/0x4e0 net/socket.c:1143
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x857/0xbc0 fs/read_write.c:584
ksys_write+0x19c/0x2c0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
ffff88802ff52400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802ff52480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802ff52500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802ff52580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802ff52600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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