audit: type=1400 audit(1519291697.442:7): avc: denied { map } for pid=4181 comm="syzkaller823800" path="/root/syzkaller823800512" dev="sda1" ino=16481 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 ================================================================== BUG: KASAN: use-after-free in __lock_acquire+0x3d4d/0x3e00 kernel/locking/lockdep.c:3310 Read of size 8 at addr ffff8801b10a0b80 by task syzkaller823800/4181 CPU: 1 PID: 4181 Comm: syzkaller823800 Not tainted 4.16.0-rc2+ #233 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23b/0x360 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __lock_acquire+0x3d4d/0x3e00 kernel/locking/lockdep.c:3310 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x96/0xc0 kernel/locking/spinlock.c:152 remove_wait_queue+0x81/0x350 kernel/sched/wait.c:50 ep_remove_wait_queue fs/eventpoll.c:596 [inline] ep_unregister_pollwait.isra.7+0x18c/0x590 fs/eventpoll.c:614 ep_free+0x13f/0x320 fs/eventpoll.c:832 ep_eventpoll_release+0x44/0x60 fs/eventpoll.c:864 __fput+0x327/0x7e0 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x199/0x270 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9bb/0x1ad0 kernel/exit.c:865 do_group_exit+0x149/0x400 kernel/exit.c:968 SYSC_exit_group kernel/exit.c:979 [inline] SyS_exit_group+0x1d/0x20 kernel/exit.c:977 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7f30c79 RSP: 002b:00000000ffb9bd1c EFLAGS: 00000292 ORIG_RAX: 00000000000000fc RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000080eb298 RDX: 0000000000000000 RSI: 00000000080d57f8 RDI: 00000000080eb2a0 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 4181: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552 __do_kmalloc_node mm/slab.c:3669 [inline] __kmalloc_node+0x47/0x70 mm/slab.c:3676 kmalloc_node include/linux/slab.h:554 [inline] kvmalloc_node+0x99/0xd0 mm/util.c:419 kvmalloc include/linux/mm.h:541 [inline] kvzalloc include/linux/mm.h:549 [inline] alloc_netdev_mqs+0x16d/0xfb0 net/core/dev.c:8299 ppp_create_interface drivers/net/ppp/ppp_generic.c:3018 [inline] ppp_unattached_ioctl drivers/net/ppp/ppp_generic.c:866 [inline] ppp_ioctl+0x1715/0x2a50 drivers/net/ppp/ppp_generic.c:602 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 C_SYSC_ioctl fs/compat_ioctl.c:1483 [inline] compat_SyS_ioctl+0x4ef/0x2a30 fs/compat_ioctl.c:1407 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 Freed by task 4181: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527 __cache_free mm/slab.c:3485 [inline] kfree+0xd9/0x260 mm/slab.c:3800 kvfree+0x36/0x60 mm/util.c:438 netdev_freemem+0x4c/0x60 net/core/dev.c:8253 netdev_release+0x10a/0x160 net/core/net-sysfs.c:1502 device_release+0x7c/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:646 [inline] kobject_release lib/kobject.c:675 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x14c/0x250 lib/kobject.c:692 put_device+0x20/0x30 drivers/base/core.c:1931 free_netdev+0x2f5/0x400 net/core/dev.c:8410 ppp_destroy_interface+0x2bc/0x390 drivers/net/ppp/ppp_generic.c:3100 ppp_release+0x12b/0x1a0 drivers/net/ppp/ppp_generic.c:415 ppp_ioctl+0x3b1/0x2a50 drivers/net/ppp/ppp_generic.c:628 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 C_SYSC_ioctl fs/compat_ioctl.c:1483 [inline] compat_SyS_ioctl+0x4ef/0x2a30 fs/compat_ioctl.c:1407 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 The buggy address belongs to the object at ffff8801b10a0000 which belongs to the cache kmalloc-4096 of size 4096 The buggy address is located 2944 bytes inside of 4096-byte region [ffff8801b10a0000, ffff8801b10a1000) The buggy address belongs to the page: page:ffffea0006c42800 count:1 mapcount:0 mapping:ffff8801b10a0000 index:0x0 compound_mapcount: 0 flags: 0x2fffc0000008100(slab|head) raw: 02fffc0000008100 ffff8801b10a0000 0000000000000000 0000000100000001 raw: ffffea0006c425a0 ffffea0006c4c8a0 ffff8801db000dc0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801b10a0a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b10a0b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801b10a0b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801b10a0c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801b10a0c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================