KASAN: use-after-free Read in j1939_sk_recv

Status: fixed on 2019/11/29 15:48
Subsystems: can
[Documentation on labels]
Fix commit: ddeeb7d4822e can: j1939: j1939_can_recv(): add priv refcounting
First crash: 1488d, last: 1488d
Cause bisection: introduced by (bisect log) :
commit 9d71dd0c70099914fcd063135da3c580865e924c
Author: The j1939 authors <>
Date: Mon Oct 8 09:48:36 2018 +0000

  can: add support of SAE J1939 protocol

Crash: KASAN: use-after-free Read in j1939_sk_recv (log)
Repro: C syz .config
Discussions (3)
Title Replies (including bot) Last reply
[PATCH v1 0/9] can: j1939: fix multiple issues found by syzbot 16 (16) 2019/11/13 10:04
[PATCH 8/9] can: j1939: j1939_can_recv(): add priv refcounting 1 (1) 2019/11/13 09:55
KASAN: use-after-free Read in j1939_sk_recv 0 (2) 2019/11/10 22:55

Sample crash report:
BUG: KASAN: use-after-free in __lock_acquire+0x3a8b/0x4a00 kernel/locking/lockdep.c:3828
Read of size 8 at addr ffff88808d6ad0c0 by task syz-executor171/8825

CPU: 1 PID: 8825 Comm: syz-executor171 Not tainted 5.4.0-rc6-next-20191108 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
 __lock_acquire+0x3a8b/0x4a00 kernel/locking/lockdep.c:3828
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:343 [inline]
 j1939_sk_recv+0x2f/0x370 net/can/j1939/socket.c:345
 j1939_can_recv+0x4e5/0x620 net/can/j1939/main.c:105
 deliver net/can/af_can.c:568 [inline]
 can_rcv_filter+0x292/0x8e0 net/can/af_can.c:602
 can_receive+0x2e7/0x530 net/can/af_can.c:659
 can_rcv+0x133/0x1b0 net/can/af_can.c:685
 __netif_receive_skb_one_core+0x113/0x1a0 net/core/dev.c:5150
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5264
 process_backlog+0x206/0x750 net/core/dev.c:6096
 napi_poll net/core/dev.c:6533 [inline]
 net_rx_action+0x508/0x1110 net/core/dev.c:6601
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
RIP: 0010:__sanitizer_cov_trace_switch+0x44/0x80 kernel/kcov.c:310
Code: 3a 48 83 f8 08 74 46 48 83 f8 10 75 27 bf 03 00 00 00 4d 8b 2c 24 31 db 4d 85 ed 74 17 49 8b 74 dc 10 48 83 c3 01 48 8b 4d 08 <e8> 47 fe ff ff 49 39 dd 75 e9 5b 41 5c 41 5d 5d c3 48 83 f8 40 bf
RSP: 0018:ffff88809caefbe8 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 0000000000000003 RCX: ffffffff8168173c
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000005
RBP: ffff88809caefc00 R08: ffff8880a19f82c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff87ae1780
R13: 000000000000000c R14: 0000000000000000 R15: ffff88809caefdf0
 do_futex+0x2bc/0x1de0 kernel/futex.c:3639
 __do_sys_futex kernel/futex.c:3705 [inline]
 __se_sys_futex kernel/futex.c:3673 [inline]
 __x64_sys_futex+0x3f7/0x590 kernel/futex.c:3673
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
RIP: 0033:0x450699
Code: e8 2c d4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 ab cc fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd88d336cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00000000006e2ca8 RCX: 0000000000450699
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006e2ca8
RBP: 00000000006e2ca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e2cac
R13: 00007ffc9e1c600f R14: 00007fd88d3379c0 R15: 0000000000000000

Allocated by task 8825:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3551
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:670 [inline]
 j1939_priv_create net/can/j1939/main.c:122 [inline]
 j1939_netdev_start+0xa4/0x550 net/can/j1939/main.c:251
 j1939_sk_bind+0x65a/0x8e0 net/can/j1939/socket.c:438
 __sys_bind+0x239/0x290 net/socket.c:1648
 __do_sys_bind net/socket.c:1659 [inline]
 __se_sys_bind net/socket.c:1657 [inline]
 __x64_sys_bind+0x73/0xb0 net/socket.c:1657
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290

Freed by task 8824:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 __j1939_priv_release net/can/j1939/main.c:154 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_priv_put+0x8b/0xb0 net/can/j1939/main.c:159
 j1939_netdev_stop+0x45/0x190 net/can/j1939/main.c:291
 j1939_sk_release+0x3bd/0x5c0 net/can/j1939/socket.c:580
 __sock_release+0xce/0x280 net/socket.c:591
 sock_close+0x1e/0x30 net/socket.c:1269
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300

The buggy address belongs to the object at ffff88808d6ac000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4288 bytes inside of
 8192-byte region [ffff88808d6ac000, ffff88808d6ae000)
The buggy address belongs to the page:
page:ffffea000235ab00 refcount:1 mapcount:0 mapping:ffff8880aa4021c0 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0002289508 ffffea0002246008 ffff8880aa4021c0
raw: 0000000000000000 ffff88808d6ac000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808d6acf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808d6ad000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808d6ad080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808d6ad100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808d6ad180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/11/10 18:38 linux-next 5591cf003452 dc438b91 .config console log report syz C ci-upstream-linux-next-kasan-gce-root
2019/11/10 14:06 linux-next 5591cf003452 dc438b91 .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.