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Message-ID: <68ee6a3f.050a0220.91a22.021b.GAE@google.com>
Date: Tue, 14 Oct 2025 08:20:31 -0700
From: syzbot <syzbot+1018672fe70298606e5f@...kaller.appspotmail.com>
To: bentiss@...nel.org, jikos@...nel.org, linux-input@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [input?] [usb?] KASAN: slab-out-of-bounds Read in
 mcp2221_raw_event (2)

syzbot has found a reproducer for the following issue on:

HEAD commit:    3a8660878839 Linux 6.18-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a705e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd
dashboard link: https://syzkaller.appspot.com/bug?extid=1018672fe70298606e5f
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=132ebb34580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140fe52f980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e767e8931970/disk-3a866087.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4cb12bdcfcea/vmlinux-3a866087.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b08acfae954d/bzImage-3a866087.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1018672fe70298606e5f@...kaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in mcp2221_raw_event+0x1070/0x10a0 drivers/hid/hid-mcp2221.c:948
Read of size 1 at addr ffff8880721cbfff by task kworker/0:7/6094

CPU: 0 UID: 0 PID: 6094 Comm: kworker/0:7 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: usb_hub_wq hub_event
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 mcp2221_raw_event+0x1070/0x10a0 drivers/hid/hid-mcp2221.c:948
 __hid_input_report.constprop.0+0x314/0x450 drivers/hid/hid-core.c:2139
 hid_irq_in+0x35e/0x870 drivers/hid/usbhid/hid-core.c:286
 __usb_hcd_giveback_urb+0x38b/0x610 drivers/usb/core/hcd.c:1661
 usb_hcd_giveback_urb+0x39b/0x450 drivers/usb/core/hcd.c:1745
 dummy_timer+0x1809/0x3a00 drivers/usb/gadget/udc/dummy_hcd.c:1995
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x202/0xad0 kernel/time/hrtimer.c:1841
 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1858
 handle_softirqs+0x219/0x8e0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:kasan_check_range+0x12/0x1b0 mm/kasan/generic.c:199
Code: 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 85 f6 0f 84 64 01 00 00 48 89 f8 41 54 <44> 0f b6 c2 48 01 f0 55 53 0f 82 d7 00 00 00 eb 0f cc cc cc 48 b8
RSP: 0018:ffffc900037b6b60 EFLAGS: 00000202
RAX: ffff888077da86b0 RBX: ffff888077da8668 RCX: ffffffff819803ae
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff888077da86b0
RBP: ffff888077da86b0 R08: 0000000000000002 R09: 0000000000000000
R10: ffff888077da866f R11: 0000000000000000 R12: ffffffff8c6df2a0
R13: ffffffff9ae57620 R14: 0000000000000000 R15: ffff888026709978
 instrument_atomic_write include/linux/instrumented.h:82 [inline]
 atomic_set include/linux/atomic/atomic-instrumented.h:67 [inline]
 osq_lock_init include/linux/osq_lock.h:25 [inline]
 __mutex_init+0xae/0x120 kernel/locking/mutex.c:53
 i2c_register_adapter+0x15d/0x1370 drivers/i2c/i2c-core-base.c:1544
 i2c_add_adapter drivers/i2c/i2c-core-base.c:1673 [inline]
 i2c_add_adapter+0x10a/0x1b0 drivers/i2c/i2c-core-base.c:1653
 devm_i2c_add_adapter+0x1b/0x90 drivers/i2c/i2c-core-base.c:1845
 mcp2221_probe+0x5f1/0xc50 drivers/hid/hid-mcp2221.c:1289
 __hid_device_probe drivers/hid/hid-core.c:2775 [inline]
 hid_device_probe+0x5ba/0x8d0 drivers/hid/hid-core.c:2812
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 hid_add_device+0x31b/0x5c0 drivers/hid/hid-core.c:2951
 usbhid_probe+0xd38/0x13f0 drivers/hid/usbhid/hid-core.c:1435
 usb_probe_interface+0x303/0xa40 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 usb_set_configuration+0x1187/0x1e20 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0xb1/0x110 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x3e0 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 usb_new_device+0xd07/0x1a60 drivers/usb/core/hub.c:2694
 hub_port_connect drivers/usb/core/hub.c:5566 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x2f34/0x4fe0 drivers/usb/core/hub.c:5952
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 5918:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 ipv6_add_addr+0x4e3/0x1fe0 net/ipv6/addrconf.c:1120
 add_addr+0xde/0x350 net/ipv6/addrconf.c:3201
 add_v4_addrs+0x642/0x980 net/ipv6/addrconf.c:3263
 addrconf_gre_config net/ipv6/addrconf.c:3545 [inline]
 addrconf_init_auto_addrs+0x51a/0x810 net/ipv6/addrconf.c:3559
 addrconf_notify+0xe93/0x19e0 net/ipv6/addrconf.c:3740
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 __dev_notify_flags+0x12c/0x2e0 net/core/dev.c:9676
 netif_change_flags+0x108/0x160 net/core/dev.c:9705
 do_setlink.constprop.0+0xb53/0x4380 net/core/rtnetlink.c:3151
 rtnl_changelink net/core/rtnetlink.c:3769 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
 rtnl_newlink+0x1446/0x2000 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6954
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x4a3/0x520 net/socket.c:2244
 __do_sys_sendto net/socket.c:2251 [inline]
 __se_sys_sendto net/socket.c:2247 [inline]
 __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2247
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880721cbc00
 which belongs to the cache kmalloc-cg-512 of size 512
The buggy address is located 583 bytes to the right of
 allocated 440-byte region [ffff8880721cbc00, ffff8880721cbdb8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x721c8
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88813ff30140 ffffea0001e68c00 dead000000000002
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813ff30140 ffffea0001e68c00 dead000000000002
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0001c87201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5796, tgid 5796 (sshd-session), ts 52056965840, free_ts 15121629475
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3039 [inline]
 allocate_slab mm/slub.c:3212 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3266
 ___slab_alloc+0xdc4/0x1ae0 mm/slub.c:4636
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4755
 __slab_alloc_node mm/slub.c:4831 [inline]
 slab_alloc_node mm/slub.c:5253 [inline]
 __do_kmalloc_node mm/slub.c:5626 [inline]
 __kmalloc_node_track_caller_noprof+0x4db/0x8a0 mm/slub.c:5736
 kmalloc_reserve+0xef/0x2c0 net/core/skbuff.c:601
 __alloc_skb+0x166/0x380 net/core/skbuff.c:670
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xe0/0x860 net/core/skbuff.c:6671
 sock_alloc_send_pskb+0x7f9/0x980 net/core/sock.c:2965
 unix_stream_sendmsg+0x39f/0x1340 net/unix/af_unix.c:2455
 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+0x7d3/0x11d0 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:738
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906
 __free_pages mm/page_alloc.c:5302 [inline]
 free_contig_range+0x183/0x4b0 mm/page_alloc.c:7146
 destroy_args+0xb69/0x12e0 mm/debug_vm_pgtable.c:958
 debug_vm_pgtable+0x1a32/0x3640 mm/debug_vm_pgtable.c:1345
 do_one_initcall+0x123/0x6e0 init/main.c:1283
 do_initcall_level init/main.c:1345 [inline]
 do_initcalls init/main.c:1361 [inline]
 do_basic_setup init/main.c:1380 [inline]
 kernel_init_freeable+0x5c8/0x920 init/main.c:1593
 kernel_init+0x1c/0x2b0 init/main.c:1483
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff8880721cbe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880721cbf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880721cbf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                                ^
 ffff8880721cc000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880721cc080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 00                	add    %al,(%rax)
   4:	0f 1f 40 00          	nopl   0x0(%rax)
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	0f 1f 40 d6          	nopl   -0x2a(%rax)
  1c:	48 85 f6             	test   %rsi,%rsi
  1f:	0f 84 64 01 00 00    	je     0x189
  25:	48 89 f8             	mov    %rdi,%rax
  28:	41 54                	push   %r12
* 2a:	44 0f b6 c2          	movzbl %dl,%r8d <-- trapping instruction
  2e:	48 01 f0             	add    %rsi,%rax
  31:	55                   	push   %rbp
  32:	53                   	push   %rbx
  33:	0f 82 d7 00 00 00    	jb     0x110
  39:	eb 0f                	jmp    0x4a
  3b:	cc                   	int3
  3c:	cc                   	int3
  3d:	cc                   	int3
  3e:	48                   	rex.W
  3f:	b8                   	.byte 0xb8


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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