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BUG: KASAN: slab-out-of-bounds in find_first_zero_bit+0x84/0x90 lib/find_bit.c:105
Read of size 8 at addr ffff8880a8d40940 by task syz-executor.0/11136

CPU: 0 PID: 11136 Comm: syz-executor.0 Not tainted 4.14.307-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:251
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:350
 kasan_report mm/kasan/report.c:408 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:429
 find_first_zero_bit+0x84/0x90 lib/find_bit.c:105
 bfs_create+0xfb/0x620 fs/bfs/dir.c:92
 lookup_open+0x77a/0x1750 fs/namei.c:3241
 do_last fs/namei.c:3334 [inline]
 path_openat+0xe08/0x2970 fs/namei.c:3571
 do_filp_open+0x179/0x3c0 fs/namei.c:3605
 do_sys_open+0x296/0x410 fs/open.c:1081
ISOFS: Unable to identify CD-ROM format.
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3
RIP: 0033:0x7fb7bb87f0f9
RSP: 002b:00007fb7b9df1168 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007fb7bb99ef80 RCX: 00007fb7bb87f0f9
RDX: 0000000000000000 RSI: 0000000000000408 RDI: 0000000020000080
RBP: 00007fb7bb8daae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe4f2a8a4f R14: 00007fb7b9df1300 R15: 0000000000022000

Allocated by task 11136:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 bfs_fill_super+0x3d5/0xd80 fs/bfs/inode.c:363
 mount_bdev+0x2b3/0x360 fs/super.c:1134
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2572 [inline]
 do_mount+0xe65/0x2a30 fs/namespace.c:2905
 SYSC_mount fs/namespace.c:3121 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3098
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3

Freed by task 8033:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 kvfree+0x45/0x50 mm/util.c:451
 xt_free_table_info+0xfe/0x170 net/netfilter/x_tables.c:1075
 __do_replace+0x3f6/0x580 net/ipv4/netfilter/arp_tables.c:932
 do_replace net/ipv6/netfilter/ip6_tables.c:1162 [inline]
 do_ip6t_set_ctl+0x256/0x3b0 net/ipv6/netfilter/ip6_tables.c:1688
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x5f/0xb0 net/netfilter/nf_sockopt.c:115
 ipv6_setsockopt+0xc0/0x120 net/ipv6/ipv6_sockglue.c:944
 tcp_setsockopt+0x7b/0xc0 net/ipv4/tcp.c:2831
 SYSC_setsockopt net/socket.c:1865 [inline]
 SyS_setsockopt+0x110/0x1e0 net/socket.c:1844
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3

The buggy address belongs to the object at ffff8880a8d40940
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
 32-byte region [ffff8880a8d40940, ffff8880a8d40960)
The buggy address belongs to the page:
page:ffffea0002a35000 count:1 mapcount:0 mapping:ffff8880a8d40000 index:0xffff8880a8d40fc1
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880a8d40000 ffff8880a8d40fc1 000000010000002c
raw: ffffea0002a7f7e0 ffffea0002be6420 ffff88813fe741c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a8d40800: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a8d40880: 05 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8880a8d40900: fb fb fb fb fc fc fc fc 07 fc fc fc fc fc fc fc
                                           ^
 ffff8880a8d40980: 05 fc fc fc fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880a8d40a00: 06 fc fc fc fc fc fc fc 06 fc fc fc fc fc fc fc
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