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BUG: KFENCE: use-after-free read in dvb_device_open+0xc4/0x340

Use-after-free read at 0xffff88823c4f0f18 (in kfence-#119):
 dvb_device_open+0xc4/0x340
 chrdev_open+0x4d9/0x600
 do_dentry_open+0x816/0x1380
 vfs_open+0x3b/0x340
 path_openat+0x2e44/0x3830
 do_file_open+0x23e/0x4a0
 do_sys_openat2+0x115/0x200
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

kfence-#119: 0xffff88823c4f0f00-0xffff88823c4f0fbf, size=192, cache=names_cache

allocated by task 30133 on cpu 1 at 882.627740s (4.928680s ago):
 do_getname+0x2e/0x250
 user_statfs+0x97/0x1c0
 __x64_sys_statfs+0x120/0x270
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

freed by task 30133 on cpu 1 at 882.627802s (4.942094s ago):
 user_statfs+0x16d/0x1c0
 __x64_sys_statfs+0x120/0x270
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 30344 Comm: syz.3.5705 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:dvb_device_open+0xc4/0x340
Code: e8 61 cf 43 fa 4d 8b 3f 4d 85 ff 0f 84 09 01 00 00 4d 8d 67 18 4c 89 e0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 e7 e8 3c cf 43 fa <4d> 8b 2c 24 4d 85 ed 0f 84 ea 00 00 00 4c 89 e8 48 c1 e8 03 80 3c
RSP: 0018:ffffc90003daf870 EFLAGS: 00010246
RAX: 1ffff1104789e1e3 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000008 RDI: 00000000ffffffff
RBP: ffff88810f58f400 R08: ffffffff8f8e50ef R09: 1ffffffff1f1ca1d
R10: dffffc0000000000 R11: fffffbfff1f1ca1e R12: ffff88823c4f0f18
R13: dffffc0000000000 R14: ffff88816e490148 R15: ffff88823c4f0f00
FS:  00007f05621e76c0(0000) GS:ffff88818dc1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88823c4f0f18 CR3: 00000001a55ea000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 chrdev_open+0x4d9/0x600
 do_dentry_open+0x816/0x1380
 vfs_open+0x3b/0x340
 path_openat+0x2e44/0x3830
 do_file_open+0x23e/0x4a0
 do_sys_openat2+0x115/0x200
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f056135d68e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f05621e6b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f05621e76c0 RCX: 00007f056135d68e
RDX: 0000000000040002 RSI: 00007f05621e6c00 RDI: ffffffffffffff9c
RBP: 00007f05621e6c00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f0561616218 R14: 00007f0561616180 R15: 00007ffdabaf28e8
 </TASK>
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