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BUG: KASAN: use-after-free in ether_addr_equal_64bits include/linux/etherdevice.h:347 [inline]
BUG: KASAN: use-after-free in eth_type_trans+0x601/0x740 net/ethernet/eth.c:167
Read of size 8 at addr ffff88807dbf0040 by task syz-executor.4/8273

CPU: 1 PID: 8273 Comm: syz-executor.4 Not tainted 5.6.0-rc5-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+0x12d/0x187 lib/dump_stack.c:118
 print_address_description.constprop.8.cold.10+0x9/0x31d mm/kasan/report.c:374
 __kasan_report.cold.11+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 ether_addr_equal_64bits include/linux/etherdevice.h:347 [inline]
 eth_type_trans+0x601/0x740 net/ethernet/eth.c:167
 napi_frags_finish net/core/dev.c:5962 [inline]
 napi_gro_frags+0x6da/0xb00 net/core/dev.c:6037
 tun_get_user+0x2412/0x37b0 drivers/net/tun.c:1980
 tun_chr_write_iter+0xaf/0x150 drivers/net/tun.c:2026
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x526/0xa70 fs/read_write.c:693
 do_iter_write+0x12a/0x510 fs/read_write.c:998
 vfs_writev+0x16d/0x2d0 fs/read_write.c:1071
 do_writev+0x112/0x2e0 fs/read_write.c:1114
 __do_sys_writev fs/read_write.c:1187 [inline]
 __se_sys_writev fs/read_write.c:1184 [inline]
 __x64_sys_writev+0x70/0xb0 fs/read_write.c:1184
 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a7d1
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 e4 b7 fb ff c3 48 83 ec 08 e8 fa 2c 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 43 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fccc2bb1ba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000207843 RCX: 000000000045a7d1
RDX: 0000000000000001 RSI: 00007fccc2bb1c00 RDI: 00000000000000f0
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007fccc2bb26d4
R13: 00000000004cab1f R14: 00000000004e4040 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea0001f6fc00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000000()
raw: 00fffe0000000000 ffffea0001f6fc08 ffffea0001f6fc08 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88807dbeff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807dbeff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88807dbf0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88807dbf0080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807dbf0100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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