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BUG: KASAN: slab-out-of-bounds in squashfs_get_id+0x1ae/0x1d0 fs/squashfs/id.c:38
Read of size 8 at addr ffff888012c2aa38 by task syz-executor.3/7557

CPU: 1 PID: 7557 Comm: syz-executor.3 Not tainted 5.10.0-rc6-next-20201201-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230
 __kasan_report mm/kasan/report.c:396 [inline]
 kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
 squashfs_get_id+0x1ae/0x1d0 fs/squashfs/id.c:38
 squashfs_new_inode fs/squashfs/inode.c:51 [inline]
 squashfs_read_inode+0x1b4/0x1b40 fs/squashfs/inode.c:120
 squashfs_fill_super+0x1140/0x23b0 fs/squashfs/super.c:310
 get_tree_bdev+0x421/0x740 fs/super.c:1344
 vfs_get_tree+0x89/0x2f0 fs/super.c:1549
 do_new_mount fs/namespace.c:2896 [inline]
 path_mount+0x12ae/0x1e70 fs/namespace.c:3227
 do_mount fs/namespace.c:3240 [inline]
 __do_sys_mount fs/namespace.c:3448 [inline]
 __se_sys_mount fs/namespace.c:3425 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3425
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x46090a
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 ad 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 8a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f459e911a88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f459e911b20 RCX: 000000000046090a
RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f459e911ae0
RBP: 00007f459e911ae0 R08: 00007f459e911b20 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
R13: 0000000020000100 R14: 0000000020000240 R15: 0000000020000200

Allocated by task 7544:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:39
 kasan_set_track mm/kasan/common.c:47 [inline]
 set_alloc_info mm/kasan/common.c:405 [inline]
 ____kasan_kmalloc mm/kasan/common.c:436 [inline]
 ____kasan_kmalloc.constprop.0+0xa0/0xd0 mm/kasan/common.c:408
 kmalloc include/linux/slab.h:557 [inline]
 kzalloc include/linux/slab.h:682 [inline]
 lsm_cred_alloc security/security.c:534 [inline]
 security_prepare_creds+0x10e/0x190 security/security.c:1633
 prepare_kernel_cred+0x465/0x800 kernel/cred.c:719
 call_usermodehelper_exec_async+0x10e/0x580 kernel/umh.c:90
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Freed by task 4903:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:39
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:47
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:358
 ____kasan_slab_free.part.0+0xe1/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:187 [inline]
 slab_free_hook mm/slub.c:1548 [inline]
 slab_free_freelist_hook+0x82/0x1d0 mm/slub.c:1586
 slab_free mm/slub.c:3157 [inline]
 kfree+0xe5/0x5c0 mm/slub.c:4156
 security_cred_free+0xc3/0x130 security/security.c:1627
 put_cred_rcu+0x122/0x4e0 kernel/cred.c:114
 rcu_do_batch kernel/rcu/tree.c:2502 [inline]
 rcu_core+0x70c/0xfc0 kernel/rcu/tree.c:2737
 __do_softirq+0x2a0/0x9f6 kernel/softirq.c:343

The buggy address belongs to the object at ffff888012c2aa28
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 8 bytes to the right of
 8-byte region [ffff888012c2aa28, ffff888012c2aa30)
The buggy address belongs to the page:
page:0000000071cac782 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888012c2a4d8 pfn:0x12c2a
flags: 0xfff00000000200(slab)
raw: 00fff00000000200 ffffea0000534480 0000000900000009 ffff888010041c80
raw: ffff888012c2a4d8 0000000080660060 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888012c2a900: fc fc fb fc fc fc fc fa fc fc fc fc 00 fc fc fc
 ffff888012c2a980: fc fa fc fc fc fc fa fc fc fc fc fa fc fc fc fc
>ffff888012c2aa00: fa fc fc fc fc fa fc fc fc fc fb fc fc fc fc fa
                                        ^
 ffff888012c2aa80: fc fc fc fc fa fc fc fc fc 00 fc fc fc fc 00 fc
 ffff888012c2ab00: fc fc fc fa fc fc fc fc 00 fc fc fc fc 00 fc fc
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