[syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_recv_frame

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4d2008430ce8 Merge tag 'docs-6.9-fixes2' of git://git.lwn...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14555ae7180000
kernel config: https://syzkaller.appspot.com/x/.config?x=98d5a8e00ed1044a
dashboard link: https://syzkaller.appspot.com/bug?extid=5c915dc5dd417b83b348
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=176f9880980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5670e5771b96/disk-4d200843.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/03314e6c8879/vmlinux-4d200843.xz
kernel image: https://storage.googleapis.com/syzbot-assets/41aca7a9505a/bzImage-4d200843.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c915d...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in l2cap_connect net/bluetooth/l2cap_core.c:3920 [inline]
BUG: KASAN: slab-use-after-free in l2cap_connect_req net/bluetooth/l2cap_core.c:4061 [inline]
BUG: KASAN: slab-use-after-free in l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4759 [inline]
BUG: KASAN: slab-use-after-free in l2cap_sig_channel net/bluetooth/l2cap_core.c:5533 [inline]
BUG: KASAN: slab-use-after-free in l2cap_recv_frame+0x19ca/0x107c0 net/bluetooth/l2cap_core.c:6793
Read of size 8 at addr ffff88802ab26000 by task kworker/u9:7/5103

CPU: 0 PID: 5103 Comm: kworker/u9:7 Not tainted 6.9.0-rc5-syzkaller-00007-g4d2008430ce8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: hci3 hci_rx_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
l2cap_connect net/bluetooth/l2cap_core.c:3920 [inline]
l2cap_connect_req net/bluetooth/l2cap_core.c:4061 [inline]
l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4759 [inline]
l2cap_sig_channel net/bluetooth/l2cap_core.c:5533 [inline]
l2cap_recv_frame+0x19ca/0x107c0 net/bluetooth/l2cap_core.c:6793
hci_acldata_packet net/bluetooth/hci_core.c:3939 [inline]
hci_rx_work+0x50f/0xca0 net/bluetooth/hci_core.c:4176
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Allocated by task 5096:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
kmalloc_trace+0x1db/0x360 mm/slub.c:3997
kmalloc include/linux/slab.h:628 [inline]
kzalloc include/linux/slab.h:749 [inline]
l2cap_conn_add+0xa9/0x9c0 net/bluetooth/l2cap_core.c:6836
l2cap_connect_cfm+0x136/0x1220 net/bluetooth/l2cap_core.c:7227
hci_connect_cfm include/net/bluetooth/hci_core.h:2007 [inline]
hci_remote_features_evt+0x68b/0xa70 net/bluetooth/hci_event.c:3778
hci_event_func net/bluetooth/hci_event.c:7542 [inline]
hci_event_packet+0xac0/0x1540 net/bluetooth/hci_event.c:7594
hci_rx_work+0x3e8/0xca0 net/bluetooth/hci_core.c:4171
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Freed by task 5102:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kfree+0x153/0x3a0 mm/slub.c:4390
l2cap_connect_cfm+0x11f/0x1220 net/bluetooth/l2cap_core.c:7223
hci_connect_cfm include/net/bluetooth/hci_core.h:2007 [inline]
hci_conn_failed+0x1f6/0x340 net/bluetooth/hci_conn.c:1230
hci_abort_conn_sync+0x583/0xde0 net/bluetooth/hci_sync.c:5567
hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:310
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
insert_work+0x3e/0x330 kernel/workqueue.c:2248
__queue_work+0xc24/0xef0 kernel/workqueue.c:2400
call_timer_fn+0x18e/0x650 kernel/time/timer.c:1793
expire_timers kernel/time/timer.c:1839 [inline]
__run_timers kernel/time/timer.c:2418 [inline]
__run_timer_base+0x695/0x8e0 kernel/time/timer.c:2429
run_timer_base kernel/time/timer.c:2438 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2448
__do_softirq+0x2c6/0x980 kernel/softirq.c:554

Second to last potentially related work creation:
kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
__kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
insert_work+0x3e/0x330 kernel/workqueue.c:2248
__queue_work+0xb00/0xef0 kernel/workqueue.c:2404
queue_work_on+0x14f/0x250 kernel/workqueue.c:2435
queue_work include/linux/workqueue.h:605 [inline]
l2cap_conn_ready net/bluetooth/l2cap_core.c:1613 [inline]
l2cap_connect_cfm+0xec2/0x1220 net/bluetooth/l2cap_core.c:7268
hci_connect_cfm include/net/bluetooth/hci_core.h:2007 [inline]
hci_remote_features_evt+0x68b/0xa70 net/bluetooth/hci_event.c:3778
hci_event_func net/bluetooth/hci_event.c:7542 [inline]
hci_event_packet+0xac0/0x1540 net/bluetooth/hci_event.c:7594
hci_rx_work+0x3e8/0xca0 net/bluetooth/hci_core.c:4171
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0xa10/0x17c0 kernel/workqueue.c:3335
worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff88802ab26000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
freed 1024-byte region [ffff88802ab26000, ffff88802ab26400)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802ab27000 pfn:0x2ab20
head: order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff80000000a40(workingset|slab|head|node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000a40 ffff888015041dc0 ffffea0000b7c210 ffffea00008af410
raw: ffff88802ab27000 000000000010000e 00000001ffffffff 0000000000000000
head: 00fff80000000a40 ffff888015041dc0 ffffea0000b7c210 ffffea00008af410
head: ffff88802ab27000 000000000010000e 00000001ffffffff 0000000000000000
head: 00fff80000000003 ffffea0000aac801 ffffea0000aac848 00000000ffffffff
head: 0000000800000000 0000000000000000 00000000ffffffff 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid -1362480974 (swapper/0), ts 1, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
__alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page+0x5f/0x160 mm/slub.c:2175
allocate_slab mm/slub.c:2338 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2391
___slab_alloc+0xc73/0x1260 mm/slub.c:3525
__slab_alloc mm/slub.c:3610 [inline]
__slab_alloc_node mm/slub.c:3663 [inline]
slab_alloc_node mm/slub.c:3835 [inline]
kmalloc_trace+0x269/0x360 mm/slub.c:3992
kmalloc include/linux/slab.h:628 [inline]
kzalloc include/linux/slab.h:749 [inline]
fqdir_init+0x59/0x170 net/ipv4/inet_fragment.c:192
lowpan_frags_init_net+0x33/0x310 net/ieee802154/6lowpan/reassembly.c:453
ops_init+0x352/0x610 net/core/net_namespace.c:136
__register_pernet_operations net/core/net_namespace.c:1243 [inline]
register_pernet_operations+0x2cb/0x660 net/core/net_namespace.c:1312
register_pernet_subsys+0x28/0x40 net/core/net_namespace.c:1353
lowpan_net_frag_init+0xb2/0x100 net/ieee802154/6lowpan/reassembly.c:538
lowpan_init_module+0x10/0x90 net/ieee802154/6lowpan/core.c:250
do_one_initcall+0x248/0x880 init/main.c:1245
do_initcall_level+0x157/0x210 init/main.c:1307
page_owner free stack trace missing

Memory state around the buggy address:
ffff88802ab25f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802ab25f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802ab26000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802ab26080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802ab26100: 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:
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
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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]

syzbot has found a reproducer for the following issue on:

HEAD commit: e8784b0aef62 Merge tag 'usb-6.11-rc6' of git://git.kernel...
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1600ea63980000
kernel config: https://syzkaller.appspot.com/x/.config?x=b3e19fd08b312452

dashboard link: https://syzkaller.appspot.com/bug?extid=5c915dc5dd417b83b348
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13ba6d1f980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10dfdadb980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e1d3f7f323a8/disk-e8784b0a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/01c01dcebf01/vmlinux-e8784b0a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/53cc8ab0ce4d/bzImage-e8784b0a.xz

Bisection is inconclusive: the first bad commit could be any of:

b79e04091010 Bluetooth: btintel: Fix null ptr deref in btintel_read_version
e7b02296fb40 Bluetooth: Remove BT_HS

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17d8bd73980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5c915d...@syzkaller.appspotmail.com

=====================================================

BUG: KMSAN: uninit-value in l2cap_conless_channel net/bluetooth/l2cap_core.c:6757 [inline]
BUG: KMSAN: uninit-value in l2cap_recv_frame+0xc9c5/0x18b10 net/bluetooth/l2cap_core.c:6831
l2cap_conless_channel net/bluetooth/l2cap_core.c:6757 [inline]
l2cap_recv_frame+0xc9c5/0x18b10 net/bluetooth/l2cap_core.c:6831
l2cap_recv_acldata+0xdd9/0x2ac0 net/bluetooth/l2cap_core.c:7514
hci_acldata_packet net/bluetooth/hci_core.c:3791 [inline]
hci_rx_work+0xb38/0x1130 net/bluetooth/hci_core.c:4028
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3312
worker_thread+0xea7/0x14d0 kernel/workqueue.c:3389
kthread+0x3e2/0x540 kernel/kthread.c:389
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
slab_post_alloc_hook mm/slub.c:3994 [inline]
slab_alloc_node mm/slub.c:4037 [inline]
kmem_cache_alloc_node_noprof+0x6bf/0xb80 mm/slub.c:4080
kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:583
__alloc_skb+0x363/0x7b0 net/core/skbuff.c:674
alloc_skb include/linux/skbuff.h:1320 [inline]
bt_skb_alloc include/net/bluetooth/bluetooth.h:493 [inline]
vhci_get_user drivers/bluetooth/hci_vhci.c:487 [inline]
vhci_write+0x128/0x910 drivers/bluetooth/hci_vhci.c:607
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xb2f/0x1550 fs/read_write.c:590
ksys_write+0x20f/0x4c0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x93/0xe0 fs/read_write.c:652
x64_sys_call+0x306a/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 5180 Comm: kworker/u9:2 Not tainted 6.11.0-rc5-syzkaller-00310-ge8784b0aef62 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: hci0 hci_rx_work
=====================================================


---

[Hillf Danton]

On Sun, 01 Sep 2024 00:39:27 -0700

> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: e8784b0aef62 Merge tag 'usb-6.11-rc6' of git://git.kernel...
> git tree: upstream

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10dfdadb980000

#syz test upstream e8784b0aef62

--- i/net/bluetooth/l2cap_core.c
+++ l/net/bluetooth/l2cap_core.c
@@ -1797,6 +1797,7 @@ static void l2cap_conn_del(struct hci_co
if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_SENT)
cancel_delayed_work_sync(&conn->info_timer);

+ cancel_work_sync(&hcon->hdev->rx_work);
hcon->l2cap_data = NULL;
conn->hchan = NULL;
l2cap_conn_put(conn);
--

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in l2cap_recv_frame

Bluetooth: hci0: command tx timeout
=====================================================
BUG: KMSAN: uninit-value in l2cap_conless_channel net/bluetooth/l2cap_core.c:6758 [inline]
BUG: KMSAN: uninit-value in l2cap_recv_frame+0xc9c5/0x18b10 net/bluetooth/l2cap_core.c:6832
l2cap_conless_channel net/bluetooth/l2cap_core.c:6758 [inline]
l2cap_recv_frame+0xc9c5/0x18b10 net/bluetooth/l2cap_core.c:6832
l2cap_recv_acldata+0xdd9/0x2ac0 net/bluetooth/l2cap_core.c:7515

CPU: 0 UID: 0 PID: 5289 Comm: kworker/u9:2 Not tainted 6.11.0-rc5-syzkaller-00310-ge8784b0aef62-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: hci0 hci_rx_work
=====================================================

Tested on:

commit: e8784b0a Merge tag 'usb-6.11-rc6' of git://git.kernel...
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1721e347980000

kernel config: https://syzkaller.appspot.com/x/.config?x=b3e19fd08b312452
dashboard link: https://syzkaller.appspot.com/bug?extid=5c915dc5dd417b83b348
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=155009eb980000

[Hillf Danton]

On Sun, 01 Sep 2024 00:39:27 -0700

> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: e8784b0aef62 Merge tag 'usb-6.11-rc6' of git://git.kernel...
> git tree: upstream

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10dfdadb980000

#syz test upstream e8784b0aef62

--- i/net/bluetooth/l2cap_core.c
+++ l/net/bluetooth/l2cap_core.c

@@ -6826,6 +6826,7 @@ static void l2cap_recv_frame(struct l2ca
break;

case L2CAP_CID_CONN_LESS:
+ *((__le16 *) skb->data) = 0;
psm = get_unaligned((__le16 *) skb->data);
skb_pull(skb, L2CAP_PSMLEN_SIZE);
l2cap_conless_channel(conn, psm, skb);
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+5c915d...@syzkaller.appspotmail.com
Tested-by: syzbot+5c915d...@syzkaller.appspotmail.com

Tested on:

commit: e8784b0a Merge tag 'usb-6.11-rc6' of git://git.kernel...
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=15b1272b980000

kernel config: https://syzkaller.appspot.com/x/.config?x=b3e19fd08b312452
dashboard link: https://syzkaller.appspot.com/bug?extid=5c915dc5dd417b83b348
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=15dc43db980000

Note: testing is done by a robot and is best-effort only.