In the Linux kernel, the following vulnerability has been resolved:
macintosh/mac_hid: fix race condition in mac_hid_toggle_emumouse
The following warning appears when running syzkaller, and this issue also
exists in the mainline code.
------------[ cut here ]------------
list_add double add: new=ffffffffa57eee28, prev=ffffffffa57eee28, next=ffffffffa5e63100.
WARNING: CPU: 0 PID: 1491 at lib/list_debug.c:35 __list_add_valid_or_report+0xf7/0x130
Modules linked in:
CPU: 0 PID: 1491 Comm: syz.1.28 Not tainted 6.6.0+ #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:__list_add_valid_or_report+0xf7/0x130
RSP: 0018:ff1100010dfb7b78 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffffffffa57eee18 RCX: ffffffff97fc9817
RDX: 0000000000040000 RSI: ffa0000002383000 RDI: 0000000000000001
RBP: ffffffffa57eee28 R08: 0000000000000001 R09: ffe21c0021bf6f2c
R10: 0000000000000001 R11: 6464615f7473696c R12: ffffffffa5e63100
R13: ffffffffa57eee28 R14: ffffffffa57eee28 R15: ff1100010dfb7d48
FS: 00007fb14398b640(0000) GS:ff11000119600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010d096005 CR4: 0000000000773ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 80000000
Call Trace:
<TASK>
input_register_handler+0xb3/0x210
mac_hid_start_emulation+0x1c5/0x290
mac_hid_toggle_emumouse+0x20a/0x240
proc_sys_call_handler+0x4c2/0x6e0
new_sync_write+0x1b1/0x2d0
vfs_write+0x709/0x950
ksys_write+0x12a/0x250
do_syscall_64+0x5a/0x110
entry_SYSCALL_64_after_hwframe+0x78/0xe2
The WARNING occurs when two processes concurrently write to the mac-hid
emulation sysctl, causing a race condition in mac_hid_toggle_emumouse().
Both processes read old_val=0, then both try to register the input handler,
leading to a double list_add of the same handler.
CPU0 CPU1
------------------------- -------------------------
vfs_write() //write 1 vfs_write() //write 1
proc_sys_write() proc_sys_write()
mac_hid_toggle_emumouse() mac_hid_toggle_emumouse()
old_val = *valp // old_val=0
old_val = *valp // old_val=0
mutex_lock_killable()
proc_dointvec() // *valp=1
mac_hid_start_emulation()
input_register_handler()
mutex_unlock()
mutex_lock_killable()
proc_dointvec()
mac_hid_start_emulation()
input_register_handler() //Trigger Warning
mutex_unlock()
Fix this by moving the old_val read inside the mutex lock region.
macintosh/mac_hid: fix race condition in mac_hid_toggle_emumouse
The following warning appears when running syzkaller, and this issue also
exists in the mainline code.
------------[ cut here ]------------
list_add double add: new=ffffffffa57eee28, prev=ffffffffa57eee28, next=ffffffffa5e63100.
WARNING: CPU: 0 PID: 1491 at lib/list_debug.c:35 __list_add_valid_or_report+0xf7/0x130
Modules linked in:
CPU: 0 PID: 1491 Comm: syz.1.28 Not tainted 6.6.0+ #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:__list_add_valid_or_report+0xf7/0x130
RSP: 0018:ff1100010dfb7b78 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffffffffa57eee18 RCX: ffffffff97fc9817
RDX: 0000000000040000 RSI: ffa0000002383000 RDI: 0000000000000001
RBP: ffffffffa57eee28 R08: 0000000000000001 R09: ffe21c0021bf6f2c
R10: 0000000000000001 R11: 6464615f7473696c R12: ffffffffa5e63100
R13: ffffffffa57eee28 R14: ffffffffa57eee28 R15: ff1100010dfb7d48
FS: 00007fb14398b640(0000) GS:ff11000119600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010d096005 CR4: 0000000000773ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 80000000
Call Trace:
<TASK>
input_register_handler+0xb3/0x210
mac_hid_start_emulation+0x1c5/0x290
mac_hid_toggle_emumouse+0x20a/0x240
proc_sys_call_handler+0x4c2/0x6e0
new_sync_write+0x1b1/0x2d0
vfs_write+0x709/0x950
ksys_write+0x12a/0x250
do_syscall_64+0x5a/0x110
entry_SYSCALL_64_after_hwframe+0x78/0xe2
The WARNING occurs when two processes concurrently write to the mac-hid
emulation sysctl, causing a race condition in mac_hid_toggle_emumouse().
Both processes read old_val=0, then both try to register the input handler,
leading to a double list_add of the same handler.
CPU0 CPU1
------------------------- -------------------------
vfs_write() //write 1 vfs_write() //write 1
proc_sys_write() proc_sys_write()
mac_hid_toggle_emumouse() mac_hid_toggle_emumouse()
old_val = *valp // old_val=0
old_val = *valp // old_val=0
mutex_lock_killable()
proc_dointvec() // *valp=1
mac_hid_start_emulation()
input_register_handler()
mutex_unlock()
mutex_lock_killable()
proc_dointvec()
mac_hid_start_emulation()
input_register_handler() //Trigger Warning
mutex_unlock()
Fix this by moving the old_val read inside the mutex lock region.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 24 Dec 2025 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: macintosh/mac_hid: fix race condition in mac_hid_toggle_emumouse The following warning appears when running syzkaller, and this issue also exists in the mainline code. ------------[ cut here ]------------ list_add double add: new=ffffffffa57eee28, prev=ffffffffa57eee28, next=ffffffffa5e63100. WARNING: CPU: 0 PID: 1491 at lib/list_debug.c:35 __list_add_valid_or_report+0xf7/0x130 Modules linked in: CPU: 0 PID: 1491 Comm: syz.1.28 Not tainted 6.6.0+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:__list_add_valid_or_report+0xf7/0x130 RSP: 0018:ff1100010dfb7b78 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffffffffa57eee18 RCX: ffffffff97fc9817 RDX: 0000000000040000 RSI: ffa0000002383000 RDI: 0000000000000001 RBP: ffffffffa57eee28 R08: 0000000000000001 R09: ffe21c0021bf6f2c R10: 0000000000000001 R11: 6464615f7473696c R12: ffffffffa5e63100 R13: ffffffffa57eee28 R14: ffffffffa57eee28 R15: ff1100010dfb7d48 FS: 00007fb14398b640(0000) GS:ff11000119600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000010d096005 CR4: 0000000000773ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 80000000 Call Trace: <TASK> input_register_handler+0xb3/0x210 mac_hid_start_emulation+0x1c5/0x290 mac_hid_toggle_emumouse+0x20a/0x240 proc_sys_call_handler+0x4c2/0x6e0 new_sync_write+0x1b1/0x2d0 vfs_write+0x709/0x950 ksys_write+0x12a/0x250 do_syscall_64+0x5a/0x110 entry_SYSCALL_64_after_hwframe+0x78/0xe2 The WARNING occurs when two processes concurrently write to the mac-hid emulation sysctl, causing a race condition in mac_hid_toggle_emumouse(). Both processes read old_val=0, then both try to register the input handler, leading to a double list_add of the same handler. CPU0 CPU1 ------------------------- ------------------------- vfs_write() //write 1 vfs_write() //write 1 proc_sys_write() proc_sys_write() mac_hid_toggle_emumouse() mac_hid_toggle_emumouse() old_val = *valp // old_val=0 old_val = *valp // old_val=0 mutex_lock_killable() proc_dointvec() // *valp=1 mac_hid_start_emulation() input_register_handler() mutex_unlock() mutex_lock_killable() proc_dointvec() mac_hid_start_emulation() input_register_handler() //Trigger Warning mutex_unlock() Fix this by moving the old_val read inside the mutex lock region. | |
| Title | macintosh/mac_hid: fix race condition in mac_hid_toggle_emumouse | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-12-24T10:32:54.084Z
Reserved: 2025-12-16T14:48:05.309Z
Link: CVE-2025-68367
Vulnrichment
No data.
NVD
Status : Received
Published: 2025-12-24T11:16:00.267
Modified: 2025-12-24T11:16:00.267
Link: CVE-2025-68367
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.