published December 8, 2025
In the Linux kernel, the following vulnerability has been resolved:
USB: usbtmc: Fix direction for 0-length ioctl control messages
The syzbot fuzzer found a problem in the usbtmc driver: When a user
submits an ioctl for a 0-length control transfer, the driver does not
check that the direction is set to OUT:
------------[ cut here ]------------
usb 3-1: BOGUS control dir, pipe 80000b80 doesn't match bRequestType fd
WARNING: CPU: 0 PID: 5100 at drivers/usb/core/urb.c:411 usb_submit_urb+0x14a7/0x1880 drivers/usb/core/urb.c:411
Modules linked in:
CPU: 0 PID: 5100 Comm: syz-executor428 Not tainted 6.3.0-syzkaller-12049-g58390c8ce1bd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
RIP: 0010:usb_submit_urb+0x14a7/0x1880 drivers/usb/core/urb.c:411
Code: 7c 24 40 e8 1b 13 5c fb 48 8b 7c 24 40 e8 21 1d f0 fe 45 89 e8 44 89 f1 4c 89 e2 48 89 c6 48 c7 c7 e0 b5 fc 8a e8 19 c8 23 fb <0f> 0b e9 9f ee ff ff e8 ed 12 5c fb 0f b6 1d 12 8a 3c 08 31 ff 41
RSP: 0018:ffffc90003d2fb00 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff8880789e9058 RCX: 0000000000000000
RDX: ffff888029593b80 RSI: ffffffff814c1447 RDI: 0000000000000001
RBP: ffff88801ea742f8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88802915e528
R13: 00000000000000fd R14: 0000000080000b80 R15: ffff8880222b3100
FS: 0000555556ca63c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9ef4d18150 CR3: 0000000073e5b000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
usb_start_wait_urb+0x101/0x4b0 drivers/usb/core/message.c:58
usb_internal_control_msg drivers/usb/core/message.c:102 [inline]
usb_control_msg+0x320/0x4a0 drivers/usb/core/message.c:153
usbtmc_ioctl_request drivers/usb/class/usbtmc.c:1954 [inline]
usbtmc_ioctl+0x1b3d/0x2840 drivers/usb/class/usbtmc.c:2097
To fix this, we must override the direction in the bRequestType field
of the control request structure when the length is 0.