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BUG: KASAN: use-after-free in perf_output_read_group kernel/events/core.c:5882 [inline]
BUG: KASAN: use-after-free in perf_output_read+0xe4e/0xfc0 kernel/events/core.c:5917
Read of size 8 at addr ffff8881d6d347e0 by task syz-executor.4/23827

CPU: 0 PID: 23827 Comm: syz-executor.4 Not tainted 4.14.125+ #6
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x10e lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xae/0x2d5 mm/kasan/report.c:393

Allocated by task 22416:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 slab_post_alloc_hook mm/slab.h:442 [inline]
 slab_alloc_node mm/slub.c:2723 [inline]
 slab_alloc mm/slub.c:2731 [inline]
 __kmalloc_track_caller+0xf1/0x310 mm/slub.c:4288
 __kmalloc_reserve.isra.0+0x2d/0xc0 net/core/skbuff.c:137
 __alloc_skb+0x105/0x550 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:980 [inline]
 kobject_uevent_env+0x6d7/0xc60 lib/kobject_uevent.c:479

Freed by task 22416:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:524
 slab_free_hook mm/slub.c:1389 [inline]
 slab_free_freelist_hook mm/slub.c:1410 [inline]
 slab_free mm/slub.c:2966 [inline]
 kfree+0xf5/0x310 mm/slub.c:3897
 skb_free_head+0x83/0xa0 net/core/skbuff.c:554
 skb_release_data+0x4ae/0x730 net/core/skbuff.c:574
 skb_release_all+0x46/0x60 net/core/skbuff.c:631
 __kfree_skb net/core/skbuff.c:645 [inline]
 consume_skb+0xbe/0x340 net/core/skbuff.c:705
 netlink_broadcast_filtered+0x2b3/0x9d0 net/netlink/af_netlink.c:1488
 kobject_uevent_env+0x81f/0xc60 lib/kobject_uevent.c:495

The buggy address belongs to the object at ffff8881d6d34780
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 96 bytes inside of
 512-byte region [ffff8881d6d34780, ffff8881d6d34980)
The buggy address belongs to the page:
page:ffffea00075b4d00 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 0000000000000000 0000000000000000 00000001000c000c
raw: ffffea00071f6080 0000000600000002 ffff8881da802c00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881d6d34680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881d6d34700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881d6d34780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8881d6d34800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881d6d34880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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