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BUG: KASAN: use-after-free in ethnl_bitmap32_not_zero net/ethtool/bitset.c:112 [inline]
BUG: KASAN: use-after-free in ethnl_compact_sanity_checks net/ethtool/bitset.c:529 [inline]
BUG: KASAN: use-after-free in ethnl_update_bitset32.part.0+0x8db/0x1820 net/ethtool/bitset.c:572
Read of size 4 at addr ffff88807762b43c by task syz-executor.5/4769

CPU: 0 PID: 4769 Comm: syz-executor.5 Not tainted 5.6.0-rc2-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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:134
 ethnl_bitmap32_not_zero net/ethtool/bitset.c:112 [inline]
 ethnl_compact_sanity_checks net/ethtool/bitset.c:529 [inline]
 ethnl_update_bitset32.part.0+0x8db/0x1820 net/ethtool/bitset.c:572
 ethnl_update_bitset32 net/ethtool/bitset.c:562 [inline]
 ethnl_update_bitset+0x4d/0x67 net/ethtool/bitset.c:734
 ethnl_update_linkmodes net/ethtool/linkmodes.c:303 [inline]
 ethnl_set_linkmodes+0x461/0xc30 net/ethtool/linkmodes.c:357
 genl_family_rcv_msg_doit net/netlink/genetlink.c:673 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:718 [inline]
 genl_rcv_msg+0x67d/0xea0 net/netlink/genetlink.c:735
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2478
 genl_rcv+0x29/0x40 net/netlink/genetlink.c:746
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x59e/0x7e0 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:672
 ____sys_sendmsg+0x753/0x880 net/socket.c:2343
 ___sys_sendmsg+0x100/0x170 net/socket.c:2397
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2430
 __do_sys_sendmsg net/socket.c:2439 [inline]
 __se_sys_sendmsg net/socket.c:2437 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2437
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c479
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f1779704c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f17797056d4 RCX: 000000000045c479
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000006
RBP: 000000000076bfc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000904 R14: 00000000004d4ff0 R15: 000000000076bfcc

The buggy address belongs to the page:
page:ffffea0001dd8ac0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1
flags: 0xfffe0000000000()
raw: 00fffe0000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88807762b300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807762b380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88807762b400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                        ^
 ffff88807762b480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807762b500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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