Message-ID: <68c85874.050a0220.50883.0016.GAE@google.com>
Date: Mon, 15 Sep 2025 11:18:28 -0700
From: syzbot <syzbot+7617e19c8a59edfbd879@...kaller.appspotmail.com>
To: bentiss@...nel.org, jikos@...nel.org, linux-input@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [input?] KASAN: stack-out-of-bounds Read in cp2112_xfer

Hello,

syzbot found the following issue on:

HEAD commit:    5cd64d4f9268 Merge tag 'ceph-for-6.17-rc6' of https://gith..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16c0db12580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4d8792ecb6308d0f
dashboard link: https://syzkaller.appspot.com/bug?extid=7617e19c8a59edfbd879
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11240762580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1552db62580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3840aa3ff580/disk-5cd64d4f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aa965f106402/vmlinux-5cd64d4f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/88839eb3c76c/bzImage-5cd64d4f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7617e19c8a59edfbd879@...kaller.appspotmail.com

==================================================================
BUG: KASAN: stack-out-of-bounds in cp2112_write_req drivers/hid/hid-cp2112.c:477 [inline]
BUG: KASAN: stack-out-of-bounds in cp2112_xfer+0x713/0xf10 drivers/hid/hid-cp2112.c:692
Read of size 34 at addr ffffc90003c0fd21 by task syz.0.17/6028

CPU: 1 UID: 0 PID: 6028 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 cp2112_write_req drivers/hid/hid-cp2112.c:477 [inline]
 cp2112_xfer+0x713/0xf10 drivers/hid/hid-cp2112.c:692
 __i2c_smbus_xfer+0x5b6/0x1e50 drivers/i2c/i2c-core-smbus.c:591
 i2c_smbus_xfer+0x275/0x3c0 drivers/i2c/i2c-core-smbus.c:546
 i2cdev_ioctl_smbus+0x43d/0x6d0 drivers/i2c/i2c-dev.c:389
 i2cdev_ioctl+0x5d3/0x7f0 drivers/i2c/i2c-dev.c:478
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f44e378eba9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcb2858658 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f44e39d5fa0 RCX: 00007f44e378eba9
RDX: 0000200000000040 RSI: 0000000000000720 RDI: 0000000000000004
RBP: 00007f44e3811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f44e39d5fa0 R14: 00007f44e39d5fa0 R15: 0000000000000003
 </TASK>

The buggy address belongs to stack of task syz.0.17/6028
 and is located at offset 33 in frame:
 i2cdev_ioctl_smbus+0x0/0x6d0 drivers/i2c/i2c-dev.c:317

This frame has 1 object:
 [32, 66) 'temp'

The buggy address belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5724d
memcg:ffff888026b61482
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff888026b61482
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 5953, tgid 5953 (syz.0.10), ts 82929749894, free_ts 82841187973
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2507
 vm_area_alloc_pages mm/vmalloc.c:3642 [inline]
 __vmalloc_area_node mm/vmalloc.c:3720 [inline]
 __vmalloc_node_range_noprof+0x97d/0x12f0 mm/vmalloc.c:3893
 __vmalloc_node_noprof+0xc2/0x110 mm/vmalloc.c:3956
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3e7/0x860 kernel/fork.c:881
 copy_process+0x54b/0x3c00 kernel/fork.c:2004
 kernel_clone+0x21e/0x840 kernel/fork.c:2605
 __do_sys_clone3 kernel/fork.c:2909 [inline]
 __se_sys_clone3+0x256/0x2d0 kernel/fork.c:2888
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5941 tgid 5941 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 vfree+0x25a/0x400 mm/vmalloc.c:3434
 kcov_put kernel/kcov.c:439 [inline]
 kcov_close+0x28/0x50 kernel/kcov.c:535
 __fput+0x449/0xa70 fs/file_table.c:468
 task_work_run+0x1d1/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:961
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x1286/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc90003c0fc00: 00 00 00 00 f1 f1 f1 f1 00 f3 f3 f3 00 00 00 00
 ffffc90003c0fc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90003c0fd00: f1 f1 f1 f1 00 00 00 00 02 f3 f3 f3 f3 f3 f3 f3
                                           ^
 ffffc90003c0fd80: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffffc90003c0fe00: 04 f2 00 00 f2 f2 00 00 f3 f3 f3 f3 00 00 00 00
==================================================================


---
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