==================================================================
BUG: KASAN: use-after-free in mcp2221_raw_event+0x103c/0x10a0 drivers/hid/hid-mcp2221.c:948
Read of size 1 at addr ffff88812b833fff by task syz.0.4917/29752

CPU: 1 UID: 0 PID: 29752 Comm: syz.0.4917 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
 mcp2221_raw_event+0x103c/0x10a0 drivers/hid/hid-mcp2221.c:948
 __hid_input_report.constprop.0+0x314/0x460 drivers/hid/hid-core.c:2139
 hid_irq_in+0x52e/0x6b0 drivers/hid/usbhid/hid-core.c:286
 __usb_hcd_giveback_urb+0x38d/0x610 drivers/usb/core/hcd.c:1657
 usb_hcd_giveback_urb+0x3ca/0x4a0 drivers/usb/core/hcd.c:1741
 dummy_timer+0xd85/0x3670 drivers/usb/gadget/udc/dummy_hcd.c:1995
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x516/0x990 kernel/time/hrtimer.c:1841
 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1858
 handle_softirqs+0x1dd/0x8f0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xed/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x8f/0xb0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:114 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:140 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:172 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:191 [inline]
RIP: 0010:kasan_check_range+0x71/0x1e0 mm/kasan/generic.c:200
Code: 37 ff 48 89 fd 48 b8 00 00 00 00 00 fc ff df 4d 89 d1 48 c1 ed 03 49 c1 e9 03 48 01 c5 49 01 c1 48 89 e8 49 8d 59 01 48 89 da <48> 29 ea 48 83 fa 10 0f 8e db 00 00 00 41 89 eb 41 83 e3 07 0f 85
RSP: 0018:ffffc9001378fcf0 EFLAGS: 00000282
RAX: fffffbfff1599aba RBX: fffffbfff1599abb RCX: ffffffff819dee25
RDX: fffffbfff1599abb RSI: 0000000000000008 RDI: ffffffff8accd5d0
RBP: fffffbfff1599aba R08: 0000000000000000 R09: fffffbfff1599aba
R10: ffffffff8accd5d7 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 000000000bebc200 R15: dffffc0000000000
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 cpumask_test_cpu include/linux/cpumask.h:649 [inline]
 cpu_online include/linux/cpumask.h:1231 [inline]
 trace_hrtimer_setup+0x55/0x1f0 include/trace/events/timer.h:193
 debug_setup_on_stack kernel/time/hrtimer.c:471 [inline]
 hrtimer_setup_sleeper_on_stack kernel/time/hrtimer.c:2083 [inline]
 hrtimer_nanosleep+0xb4/0x360 kernel/time/hrtimer.c:2161
 common_nsleep+0xa1/0xd0 kernel/time/posix-timers.c:1352
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1398 [inline]
 __se_sys_clock_nanosleep kernel/time/posix-timers.c:1375 [inline]
 __x64_sys_clock_nanosleep+0x336/0x480 kernel/time/posix-timers.c:1375
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x570 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efc90cec84e
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:00007efc8f785f38 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 00007efc8f7876c0 RCX: 00007efc90cec84e
RDX: 00007efc8f785f90 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000040
R13: 0000000000000000 R14: 00007efc90fa5fa0 R15: 00007fff75d912d8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12b833
flags: 0x200000000000000(node=0|zone=2)
raw: 0200000000000000 0000000000000000 00000000ffffffff 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 29472, tgid 29472 (fido_id), ts 2571458629660, free_ts 2619250966792
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1e1/0x250 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0xd57/0x3b20 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x269/0x2230 mm/page_alloc.c:5240
 alloc_pages_mpol+0xe8/0x410 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab mm/slub.c:3248 [inline]
 new_slab+0x2c4/0x440 mm/slub.c:3302
 ___slab_alloc+0xda3/0x1ca0 mm/slub.c:4656
 __kmem_cache_alloc_bulk+0x20f/0x700 mm/slub.c:7431
 refill_sheaf mm/slub.c:2650 [inline]
 __prefill_sheaf_pfmemalloc+0x42/0x90 mm/slub.c:5328
 kmem_cache_prefill_sheaf+0x1b7/0x420 mm/slub.c:5422
 mt_get_sheaf lib/maple_tree.c:189 [inline]
 mas_alloc_nodes+0x2c3/0x390 lib/maple_tree.c:1140
 mas_preallocate+0x39c/0xf10 lib/maple_tree.c:5194
 vma_iter_prealloc mm/vma.h:505 [inline]
 __split_vma+0x33d/0xdf0 mm/vma.c:524
 split_vma mm/vma.c:594 [inline]
 vma_modify+0x10c9/0x22c0 mm/vma.c:1672
 vma_modify_flags+0x1f2/0x350 mm/vma.c:1692
 mprotect_fixup+0x209/0xb40 mm/mprotect.c:756
 do_mprotect_pkey+0x9e1/0xe70 mm/mprotect.c:930
page last free pid 25872 tgid 25872 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7d1/0x1010 mm/page_alloc.c:2973
 discard_slab mm/slub.c:3346 [inline]
 __put_partials+0x127/0x160 mm/slub.c:3886
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x4e/0x70 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0x307/0x9a0 mm/slub.c:5764
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:608
 __alloc_skb+0x186/0x410 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xe0/0x810 net/core/skbuff.c:6714
 sock_alloc_send_pskb+0x801/0x980 net/core/sock.c:2995
 unix_dgram_sendmsg+0x3c7/0x1820 net/unix/af_unix.c:2130
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 sock_write_iter+0x566/0x610 net/socket.c:1195
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x6ac/0x1070 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x570 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88812b833e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812b833f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812b833f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff88812b834000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812b834080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	ff 48 89             	decl   -0x77(%rax)
   3:	fd                   	std
   4:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
   b:	fc ff df
   e:	4d 89 d1             	mov    %r10,%r9
  11:	48 c1 ed 03          	shr    $0x3,%rbp
  15:	49 c1 e9 03          	shr    $0x3,%r9
  19:	48 01 c5             	add    %rax,%rbp
  1c:	49 01 c1             	add    %rax,%r9
  1f:	48 89 e8             	mov    %rbp,%rax
  22:	49 8d 59 01          	lea    0x1(%r9),%rbx
  26:	48 89 da             	mov    %rbx,%rdx
* 29:	48 29 ea             	sub    %rbp,%rdx <-- trapping instruction
  2c:	48 83 fa 10          	cmp    $0x10,%rdx
  30:	0f 8e db 00 00 00    	jle    0x111
  36:	41 89 eb             	mov    %ebp,%r11d
  39:	41 83 e3 07          	and    $0x7,%r11d
  3d:	0f                   	.byte 0xf
  3e:	85                   	.byte 0x85