------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#1: syz.1.616/8801
Modules linked in:
CPU: 1 UID: 0 PID: 8801 Comm: syz.1.616 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25
Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 bb d1 13 fd 48 8d 3d c4 9f 89 0b 67 48 0f b9 3a eb 4a e8 a8 d1 13 fd 48 8d 3d c1 9f 89 0b <67> 48 0f b9 3a eb 37 e8 95 d1 13 fd 48 8d 3d be 9f 89 0b 67 48 0f
RSP: 0000:ffffc90003597738 EFLAGS: 00010287
RAX: ffffffff84b1d208 RBX: 0000000000000002 RCX: 0000000000080000
RDX: ffffc9000f8a3000 RSI: 0000000000000843 RDI: ffffffff903b71d0
RBP: 0000000000000000 R08: ffff88807c1a9ec0 R09: 0000000000000005
R10: 0000000000000004 R11: 0000000000000002 R12: ffffffff8c973988
R13: dffffc0000000000 R14: ffff8880596391a0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888125393000(0063) knlGS:00000000f53fbb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000080026018 CR3: 0000000025612000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:366 [inline]
 refcount_inc include/linux/refcount.h:383 [inline]
 kref_get include/linux/kref.h:45 [inline]
 kobject_get+0xfa/0x120 lib/kobject.c:643
 i2c_get_adapter+0x6d/0xa0 drivers/i2c/i2c-core-base.c:2612
 i2cdev_open+0x48/0x180 drivers/i2c/i2c-dev.c:603
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_compat_sys_openat fs/open.c:1432 [inline]
 __se_compat_sys_openat fs/open.c:1430 [inline]
 __ia32_compat_sys_openat+0x131/0x160 fs/open.c:1430
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 do_int80_emulation+0x181/0x530 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:621
RIP: 0023:0xf718616b
Code: 57 56 53 8b 44 24 14 f6 00 08 75 23 8b 44 24 18 8b 5c 24 1c 8b 4c 24 20 8b 54 24 24 8b 74 24 28 8b 7c 24 2c 8b 6c 24 30 cd 80 <5b> 5e 5f 5d c3 5b 5e 5f 5d e9 f7 a1 ff ff 66 90 66 90 66 90 90 53
RSP: 002b:00000000f53fb03c EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000f53fb100
RDX: 0000000000000402 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	eb 66                	jmp    0x68
   2:	85 db                	test   %ebx,%ebx
   4:	74 3e                	je     0x44
   6:	83 fb 01             	cmp    $0x1,%ebx
   9:	75 4c                	jne    0x57
   b:	e8 bb d1 13 fd       	call   0xfd13d1cb
  10:	48 8d 3d c4 9f 89 0b 	lea    0xb899fc4(%rip),%rdi        # 0xb899fdb
  17:	67 48 0f b9 3a       	ud1    (%edx),%rdi
  1c:	eb 4a                	jmp    0x68
  1e:	e8 a8 d1 13 fd       	call   0xfd13d1cb
  23:	48 8d 3d c1 9f 89 0b 	lea    0xb899fc1(%rip),%rdi        # 0xb899feb
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 37                	jmp    0x68
  31:	e8 95 d1 13 fd       	call   0xfd13d1cb
  36:	48 8d 3d be 9f 89 0b 	lea    0xb899fbe(%rip),%rdi        # 0xb899ffb
  3d:	67                   	addr32
  3e:	48                   	rex.W
  3f:	0f                   	.byte 0xf