use-after-free. [libata/block]

[Dave Jones]

Found this in the logs this morning after an overnight fuzz run..

BUG: KASAN: use-after-free in __lock_acquire+0x1aa/0x1970
Read of size 8 at addr ffff880406805e30 by task trinity-c8/25954

CPU: 1 PID: 25954 Comm: trinity-c8 Not tainted 4.13.0-rc2-think+ #1 
Call Trace:
 <IRQ>
 dump_stack+0x68/0xa1
 print_address_description+0xd9/0x270
 kasan_report+0x257/0x370
 ? __lock_acquire+0x1aa/0x1970
 __asan_load8+0x54/0x90
 __lock_acquire+0x1aa/0x1970
 ? save_stack+0xb1/0xd0
 ? save_stack_trace+0x1b/0x20
 ? save_stack+0x46/0xd0
 ? try_to_wake_up+0x9b/0xa20
 ? end_swap_bio_read+0xbe/0x1a0
 ? debug_check_no_locks_freed+0x1b0/0x1b0
 ? scsi_softirq_done+0x1a3/0x1d0
 ? __blk_mq_complete_request+0x14a/0x2a0
 ? blk_mq_complete_request+0x33/0x40
 ? scsi_mq_done+0x4e/0x190
 ? ata_scsi_qc_complete+0x15b/0x700
 ? __ata_qc_complete+0x16d/0x2e0
 ? ata_qc_complete+0x1a4/0x740
 ? ata_qc_complete_multiple+0xeb/0x140
 ? ahci_handle_port_interrupt+0x19e/0xa10
 ? ahci_handle_port_intr+0xd9/0x130
 ? ahci_single_level_irq_intr+0x62/0x90
 ? __handle_irq_event_percpu+0x6e/0x450
 ? handle_irq_event_percpu+0x70/0xf0
 ? handle_irq_event+0x5a/0x90
 ? handle_edge_irq+0xd9/0x2f0
 ? handle_irq+0xb4/0x190
 ? do_IRQ+0x67/0x140
 ? common_interrupt+0x97/0x97
 ? do_syscall_64+0x45/0x260
 ? entry_SYSCALL64_slow_path+0x25/0x25
 lock_acquire+0xfc/0x220
 ? lock_acquire+0xfc/0x220
 ? try_to_wake_up+0x9b/0xa20
 _raw_spin_lock_irqsave+0x40/0x80
 ? try_to_wake_up+0x9b/0xa20
 try_to_wake_up+0x9b/0xa20
 ? rcu_read_lock_sched_held+0x8f/0xa0
 ? kmem_cache_free+0x2d3/0x300
 ? migrate_swap_stop+0x3f0/0x3f0
 ? mempool_free+0x5f/0xd0
 wake_up_process+0x15/0x20
 end_swap_bio_read+0xc6/0x1a0
 bio_endio+0x12f/0x300
 blk_update_request+0x12e/0x5c0
 scsi_end_request+0x63/0x2f0
 scsi_io_completion+0x3f3/0xa50
 ? scsi_end_request+0x2f0/0x2f0
 ? lock_downgrade+0x2c0/0x2c0
 ? lock_acquire+0xfc/0x220
 ? blk_stat_add+0x62/0x340
 ? scsi_handle_queue_ramp_up+0x42/0x1e0
 scsi_finish_command+0x1b1/0x220
 scsi_softirq_done+0x1a3/0x1d0
 __blk_mq_complete_request+0x14a/0x2a0
 ? scsi_prep_state_check.isra.26+0xa0/0xa0
 blk_mq_complete_request+0x33/0x40
 scsi_mq_done+0x4e/0x190
 ? scsi_prep_state_check.isra.26+0xa0/0xa0
 ata_scsi_qc_complete+0x15b/0x700
 ? lock_downgrade+0x2c0/0x2c0
 ? msleep_interruptible+0xb0/0xb0
 ? ata_scsi_activity_show+0xb0/0xb0
 ? trace_hardirqs_off_caller+0x70/0x110
 ? trace_hardirqs_off+0xd/0x10
 ? _raw_spin_unlock_irqrestore+0x4b/0x50
 ? intel_unmap+0x20b/0x300
 ? intel_unmap_sg+0x9e/0xc0
 __ata_qc_complete+0x16d/0x2e0
 ? intel_unmap+0x300/0x300
 ata_qc_complete+0x1a4/0x740
 ata_qc_complete_multiple+0xeb/0x140
 ahci_handle_port_interrupt+0x19e/0xa10
 ? ahci_single_level_irq_intr+0x57/0x90
 ahci_handle_port_intr+0xd9/0x130
 ahci_single_level_irq_intr+0x62/0x90
 ? ahci_handle_port_intr+0x130/0x130
 __handle_irq_event_percpu+0x6e/0x450
 handle_irq_event_percpu+0x70/0xf0
 ? __handle_irq_event_percpu+0x450/0x450
 ? lock_contended+0x810/0x810
 ? handle_edge_irq+0x30/0x2f0
 ? do_raw_spin_unlock+0x97/0x130
 handle_irq_event+0x5a/0x90
 handle_edge_irq+0xd9/0x2f0
 handle_irq+0xb4/0x190
 do_IRQ+0x67/0x140
 common_interrupt+0x97/0x97
RIP: 0010:do_syscall_64+0x45/0x260
RSP: 0018:ffff8803b2bd7f08 EFLAGS: 00000246
 ORIG_RAX: ffffffffffffff1e
RAX: 0000000000000000 RBX: ffff8803b2bd7f58 RCX: ffffffff81146032
RDX: 0000000000000007 RSI: dffffc0000000000 RDI: ffff88044e6c9cc0
RBP: ffff8803b2bd7f48 R08: ffff88046b21d1c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000023
R13: ffff88044e6c9cc0 R14: ffff8803b2bd7fd0 R15: 00000000cccccccd
 </IRQ>
 ? trace_hardirqs_on_caller+0x182/0x260
 ? do_syscall_64+0x41/0x260
 entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x7f80c5932230
RSP: 002b:00007fff521ac2e8 EFLAGS: 00000246
 ORIG_RAX: 0000000000000023
RAX: ffffffffffffffda RBX: 00007f80c5ff6058 RCX: 00007f80c5932230
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fff521ac2f0
RBP: 0000000000006562 R08: 00007f80c5c130a4 R09: 00007f80c5c13120
R10: 0000000000000001 R11: 0000000000000246 R12: 000000000000005a
R13: 00007f80c5ff6058 R14: 0000004df61cd3a0 R15: 00000000cccccccd

Allocated by task 14480:
 save_stack_trace+0x1b/0x20
 save_stack+0x46/0xd0
 kasan_kmalloc+0xad/0xe0
 kasan_slab_alloc+0x12/0x20
 kmem_cache_alloc+0xe0/0x2f0
 copy_process.part.44+0xbe0/0x2f90
 _do_fork+0x173/0x8a0
 SyS_clone+0x19/0x20
 do_syscall_64+0xea/0x260
 return_from_SYSCALL_64+0x0/0x7a

Freed by task 0:
 save_stack_trace+0x1b/0x20
 save_stack+0x46/0xd0
 kasan_slab_free+0x72/0xc0
 kmem_cache_free+0xa8/0x300
 free_task+0x69/0x70
 __put_task_struct+0xdc/0x220
 delayed_put_task_struct+0x59/0x1a0
 rcu_process_callbacks+0x49a/0x1580
 __do_softirq+0x109/0x5bc

The buggy address belongs to the object at ffff8804068055c0
 which belongs to the cache task_struct of size 6848
The buggy address is located 2160 bytes inside of
 6848-byte region [ffff8804068055c0, ffff880406807080)
The buggy address belongs to the page:
page:ffffea00101a0000 count:1 mapcount:0 mapping:          (null) index:0x0
 compound_mapcount: 0
flags: 0x8000000000008100(slab|head)
raw: 8000000000008100 0000000000000000 0000000000000000 0000000100040004
raw: ffffea0006f6f420 ffffea0005311820 ffff880467e68e40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff880406805d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880406805d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff880406805e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff880406805e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880406805f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Disabling lock debugging due to kernel taint