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BUG: KASAN: use-after-free in instrument_atomic_write include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_sub_return include/asm-generic/atomic-instrumented.h:160 [inline]
BUG: KASAN: use-after-free in skb_release_data+0x11a/0x910 net/core/skbuff.c:599
Write of size 4 at addr ffff888060ad58e0 by task syz-executor.0/21397

CPU: 1 PID: 21397 Comm: syz-executor.0 Not tainted 5.8.0-rc1-syzkaller #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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 instrument_atomic_write include/linux/instrumented.h:71 [inline]
 atomic_sub_return include/asm-generic/atomic-instrumented.h:160 [inline]
 skb_release_data+0x11a/0x910 net/core/skbuff.c:599
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 kfree_skb.part.0+0xc2/0x350 net/core/skbuff.c:696
 kfree_skb+0x7d/0x100 include/linux/refcount.h:270
 ip6_tnl_start_xmit+0x717/0x16f0 net/ipv6/ip6_tunnel.c:1460
 __netdev_start_xmit include/linux/netdevice.h:4611 [inline]
 netdev_start_xmit include/linux/netdevice.h:4625 [inline]
 xmit_one net/core/dev.c:3556 [inline]
 dev_hard_start_xmit+0x193/0x950 net/core/dev.c:3572
 __dev_queue_xmit+0x2091/0x2d60 net/core/dev.c:4131
 packet_sendmsg_spkt+0xd9a/0x13b0 net/packet/af_packet.c:1992
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cb19
Code: Bad RIP value.
RSP: 002b:00007f1f9ad9dc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000502440 RCX: 000000000045cb19
RDX: 0000000000000044 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000a39 R14: 00000000004cd203 R15: 00007f1f9ad9e6d4

Allocated by task 21397:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0xae/0x550 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1083 [inline]
 sock_wmalloc+0xd0/0x120 net/core/sock.c:2205
 packet_sendmsg_spkt+0x483/0x13b0 net/packet/af_packet.c:1939
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 21397:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 skb_free_head net/core/skbuff.c:590 [inline]
 skb_release_data+0x6d9/0x910 net/core/skbuff.c:610
 skb_release_all net/core/skbuff.c:664 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 kfree_skb.part.0+0xc2/0x350 net/core/skbuff.c:696
 kfree_skb+0x7d/0x100 include/linux/refcount.h:270
 packet_rcv_spkt+0xe2/0x530 net/packet/af_packet.c:1855
 dev_queue_xmit_nit+0x7f6/0xac0 net/core/dev.c:2355
 xmit_one net/core/dev.c:3552 [inline]
 dev_hard_start_xmit+0xaa/0x950 net/core/dev.c:3572
 __dev_queue_xmit+0x2091/0x2d60 net/core/dev.c:4131
 packet_sendmsg_spkt+0xd9a/0x13b0 net/packet/af_packet.c:1992
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2352
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2406
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2439
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888060ad5800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 224 bytes inside of
 512-byte region [ffff888060ad5800, ffff888060ad5a00)
The buggy address belongs to the page:
page:ffffea000182b540 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00015c49c8 ffffea00023f4d48 ffff8880aa000a80
raw: 0000000000000000 ffff888060ad5000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888060ad5780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888060ad5800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888060ad5880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888060ad5900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888060ad5980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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