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BUG: KASAN: use-after-free in ethnl_update_bitset32+0x17d7/0x1850
Read of size 4 at addr ffff8881ebafcc3c by task syz-executor.4/4480

CPU: 1 PID: 4480 Comm: syz-executor.4 Not tainted 5.6.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 dump_stack+0x191/0x20f
 print_address_description.constprop.0.cold+0x72/0x369
 __kasan_report.cold+0x1b/0x32
 kasan_report+0x12/0x20
 __asan_report_load4_noabort+0x14/0x20
 ethnl_update_bitset32+0x17d7/0x1850
 ethnl_update_bitset+0x41/0x50
 ethnl_set_linkmodes+0x50d/0xc40
 genl_rcv_msg+0x71f/0xf80
 netlink_rcv_skb+0x186/0x470
 genl_rcv+0x28/0x40
 netlink_unicast+0x589/0x880
 netlink_sendmsg+0x922/0xe90
 sock_sendmsg+0xd2/0x120
 ____sys_sendmsg+0x679/0x880
 ___sys_sendmsg+0x11d/0x1b0
 __x64_sys_sendmsg+0x149/0x230
 do_syscall_64+0xf6/0x240
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f8ffce63f69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8ffc1e40c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8ffcf91f80 RCX: 00007f8ffce63f69
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 00007f8ffceb04a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f8ffcf91f80 R15: 00007ffd5e263e68

Allocated by task 4409:
 save_stack+0x21/0x80
 __kasan_kmalloc.constprop.0+0xea/0x100
 kasan_slab_alloc+0xf/0x20
 kmem_cache_alloc+0x11a/0x3b0
 getname_flags.part.0+0x53/0x4e0
 user_path_at_empty+0xac/0x110
 vfs_statx+0x130/0x220
 __do_sys_newfstatat+0xad/0x130
 __x64_sys_newfstatat+0x96/0xf0
 do_syscall_64+0xf6/0x240
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4409:
 save_stack+0x21/0x80
 __kasan_slab_free+0xfe/0x140
 kasan_slab_free+0xe/0x10
 kmem_cache_free+0x83/0x310
 putname+0xef/0x130
 filename_lookup+0x3a1/0x540
 user_path_at_empty+0xc7/0x110
 vfs_statx+0x130/0x220
 __do_sys_newfstatat+0xad/0x130
 __x64_sys_newfstatat+0x96/0xf0
 do_syscall_64+0xf6/0x240
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881ebafc840
 which belongs to the cache names_cache of size 4096
The buggy address is located 1020 bytes inside of
 4096-byte region [ffff8881ebafc840, ffff8881ebafd840)
The buggy address belongs to the page:
page:ffffea0007aebf00 refcount:1 mapcount:0 mapping:ffff8881f55faa80 index:0x0 compound_mapcount: 0
flags: 0x17ffe0000010200(slab|head)
raw: 017ffe0000010200 ffffea0007b02c08 ffffea0007aec208 ffff8881f55faa80
raw: 0000000000000000 ffff8881ebafc840 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881ebafcb00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881ebafcb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881ebafcc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff8881ebafcc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881ebafcd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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