UBUNTU-CVE-2025-68367
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.
02 / AFFECTED SOFTWARE
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/stable/c/1e4b207ffe54cf33a4b7a2912c4110f89c73bf3f
- https://git.kernel.org/stable/c/230621ffdb361d15cd3ef92d8b4fa8d314f4fad4
- https://git.kernel.org/stable/c/388391dd1cc567fcf0b372b63d414c119d23e911
- https://git.kernel.org/stable/c/48a7d427eb65922b3f17fbe00e2bbc7cb9eac381
- https://ubuntu.com/security/CVE-2025-68367
- https://ubuntu.com/security/notices/USN-8094-1
- https://ubuntu.com/security/notices/USN-8094-2
- https://ubuntu.com/security/notices/USN-8094-3
- https://ubuntu.com/security/notices/USN-8094-4
- https://ubuntu.com/security/notices/USN-8094-5
- https://ubuntu.com/security/notices/USN-8096-1
- https://ubuntu.com/security/notices/USN-8096-2
- https://ubuntu.com/security/notices/USN-8096-3
- https://ubuntu.com/security/notices/USN-8096-4
- https://ubuntu.com/security/notices/USN-8096-5
- https://ubuntu.com/security/notices/USN-8116-1
- https://ubuntu.com/security/notices/USN-8141-1
- https://ubuntu.com/security/notices/USN-8152-1
- https://ubuntu.com/security/notices/USN-8163-1
- https://ubuntu.com/security/notices/USN-8163-2
- https://ubuntu.com/security/notices/USN-8179-1
- https://ubuntu.com/security/notices/USN-8179-2
- https://ubuntu.com/security/notices/USN-8179-3
- https://ubuntu.com/security/notices/USN-8179-4
- https://ubuntu.com/security/notices/USN-8184-1
- https://ubuntu.com/security/notices/USN-8185-1
- https://ubuntu.com/security/notices/USN-8185-2
- https://ubuntu.com/security/notices/USN-8203-1
- https://ubuntu.com/security/notices/USN-8204-1
- https://ubuntu.com/security/notices/USN-8243-1
- https://ubuntu.com/security/notices/USN-8258-1
- https://ubuntu.com/security/notices/USN-8260-1
- https://ubuntu.com/security/notices/USN-8261-1
- https://ubuntu.com/security/notices/USN-8265-1
- https://ubuntu.com/security/notices/USN-8440-1
- https://www.cve.org/CVERecord?id=CVE-2025-68367