syzbot

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BUG: KASAN: use-after-free in atomic_sub_return include/asm-generic/atomic-instrumented.h:159 [inline]
BUG: KASAN: use-after-free in atomic_dec_return include/linux/atomic-fallback.h:455 [inline]
BUG: KASAN: use-after-free in j1939_sock_pending_del+0x26/0x80 net/can/j1939/socket.c:73
Write of size 4 at addr ffff8880937f24c0 by task ksoftirqd/0/9

CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.4.0-rc6+ #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
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192
 __kasan_check_write+0x14/0x20 mm/kasan/common.c:98
 atomic_sub_return include/asm-generic/atomic-instrumented.h:159 [inline]
 atomic_dec_return include/linux/atomic-fallback.h:455 [inline]
 j1939_sock_pending_del+0x26/0x80 net/can/j1939/socket.c:73
 __j1939_session_drop net/can/j1939/transport.c:257 [inline]
 j1939_session_destroy net/can/j1939/transport.c:270 [inline]
 __j1939_session_release net/can/j1939/transport.c:280 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_session_put+0x107/0x180 net/can/j1939/transport.c:285
 j1939_xtp_rx_abort_one+0xc7/0x100 net/can/j1939/transport.c:1261
 j1939_xtp_rx_abort net/can/j1939/transport.c:1269 [inline]
 j1939_tp_cmd_recv net/can/j1939/transport.c:1940 [inline]
 j1939_tp_recv+0x783/0x9b0 net/can/j1939/transport.c:1973
 j1939_can_recv+0x4bb/0x620 net/can/j1939/main.c:100
 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:4929
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5043
 process_backlog+0x206/0x750 net/core/dev.c:5874
 napi_poll net/core/dev.c:6311 [inline]
 net_rx_action+0x508/0x1120 net/core/dev.c:6379
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 run_ksoftirqd kernel/softirq.c:603 [inline]
 run_ksoftirqd+0x8e/0x110 kernel/softirq.c:595
 smpboot_thread_fn+0x6a3/0xa40 kernel/smpboot.c:165
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 9288:
 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
 __do_kmalloc mm/slab.c:3655 [inline]
 __kmalloc+0x163/0x770 mm/slab.c:3664
 kmalloc include/linux/slab.h:561 [inline]
 sk_prot_alloc+0x23a/0x310 net/core/sock.c:1605
 sk_alloc+0x39/0xf70 net/core/sock.c:1659
 can_create+0x1e7/0x4b0 net/can/af_can.c:157
 __sock_create+0x3d8/0x730 net/socket.c:1418
 sock_create net/socket.c:1469 [inline]
 __sys_socket+0x103/0x220 net/socket.c:1511
 __do_sys_socket net/socket.c:1520 [inline]
 __se_sys_socket net/socket.c:1518 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1518
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
 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:3425 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3756
 sk_prot_free net/core/sock.c:1642 [inline]
 __sk_destruct+0x4aa/0x680 net/core/sock.c:1726
 sk_destruct+0xd5/0x110 net/core/sock.c:1741
 __sk_free+0xfb/0x360 net/core/sock.c:1752
 sock_wfree+0xed/0x190 net/core/sock.c:1968
 skb_release_head_state+0xeb/0x260 net/core/skbuff.c:652
 skb_release_all+0x16/0x60 net/core/skbuff.c:663
 __kfree_skb net/core/skbuff.c:679 [inline]
 kfree_skb net/core/skbuff.c:697 [inline]
 kfree_skb+0x101/0x3c0 net/core/skbuff.c:691
 skb_queue_purge+0x19/0x40 net/core/skbuff.c:3078
 j1939_session_destroy net/can/j1939/transport.c:269 [inline]
 __j1939_session_release net/can/j1939/transport.c:280 [inline]
 kref_put include/linux/kref.h:65 [inline]
 j1939_session_put+0x97/0x180 net/can/j1939/transport.c:285
 j1939_xtp_rx_abort_one+0xc7/0x100 net/can/j1939/transport.c:1261
 j1939_xtp_rx_abort net/can/j1939/transport.c:1269 [inline]
 j1939_tp_cmd_recv net/can/j1939/transport.c:1940 [inline]
 j1939_tp_recv+0x783/0x9b0 net/can/j1939/transport.c:1973
 j1939_can_recv+0x4bb/0x620 net/can/j1939/main.c:100
 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:4929
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5043
 process_backlog+0x206/0x750 net/core/dev.c:5874
 napi_poll net/core/dev.c:6311 [inline]
 net_rx_action+0x508/0x1120 net/core/dev.c:6379
 __do_softirq+0x262/0x98c kernel/softirq.c:292

The buggy address belongs to the object at ffff8880937f2000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1216 bytes inside of
 2048-byte region [ffff8880937f2000, ffff8880937f2800)
The buggy address belongs to the page:
page:ffffea00024dfc80 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000248d788 ffff8880aa401948 ffff8880aa400e00
raw: 0000000000000000 ffff8880937f2000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880937f2380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880937f2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880937f2480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8880937f2500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880937f2580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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