CVE: CVE-2025-68327
Published: 2025-12-22
Description: In the Linux kernel, the following vulnerability has been resolved:

usb: renesas_usbhs: Fix synchronous external abort on unbind

A synchronous external abort occurs on the Renesas RZ/G3S SoC if unbind is
executed after the configuration sequence described above:

modprobe usb_f_ecm
modprobe libcomposite
modprobe configfs
cd /sys/kernel/config/usb_gadget
mkdir -p g1
cd g1
echo "0x1d6b" > idVendor
echo "0x0104" > idProduct
mkdir -p strings/0x409
echo "[PII_REDACTED]" > strings/0x409/serialnumber
echo "Renesas." > strings/0x409/manufacturer
echo "Ethernet Gadget" > strings/0x409/product
mkdir -p functions/ecm.usb0
mkdir -p configs/c.1
mkdir -p configs/c.1/strings/0x409
echo "ECM" > configs/c.1/strings/0x409/configuration

if [ ! -L configs/c.1/ecm.usb0 ]; then
        ln -s functions/ecm.usb0 configs/c.1
fi

echo 11e20000.usb > UDC
echo 11e20000.usb > /sys/bus/platform/drivers/renesas_usbhs/unbind

The displayed trace is as follows:

 Internal error: synchronous external abort: [PII_REDACTED] [#1] SMP
 CPU: 0 UID: 0 PID: 188 Comm: sh Tainted: G M 6.17.0-rc7-next-20[PII_REDACTED]0-g41050493b2bd #55 PREEMPT
 Tainted: [M]=MACHINE_CHECK
 Hardware name: Renesas SMARC EVK version 2 based on r9a08g045s33 (DT)
 pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : usbhs_sys_function_pullup+0x10/0x40 [renesas_usbhs]
 lr : usbhsg_update_pullup+0x3c/0x68 [renesas_usbhs]
 sp : ffff8000838b3920
 x29: ffff8000838b3920 x28: ffff00000d585780 x27: [PII_REDACTED]
 x26: [PII_REDACTED] x25: [PII_REDACTED] x24: ffff00000c3e3810
 x23: ffff00000d5e5c80 x22: ffff00000d5e5d40 x21: [PII_REDACTED]
 x20: [PII_REDACTED] x19: ffff00000d5e5c80 x18: [PII_REDACTED]
 x17: 2e[PII_REDACTED]6531 x16: 312d7968703a7968 x15: 3d454d414e5f4344
 x14:[PII_REDACTED]00002c x13: [PII_REDACTED] x12: [PII_REDACTED]
 x11: ffff00000f358f38 x10: ffff00000f358db0 x9 : ffff00000b41f418
 x8 : [PII_REDACTED] x7 : 7f7f7f7f7f7f7f7f x6 : fefefeff6364626d
 x5 : [PII_REDACTED] x4 : 000000004b5ccb9d x3 : [PII_REDACTED]
 x2 : [PII_REDACTED] x1 : ffff[PII_REDACTED]00 x0 : ffff00000d5e5c80
 Call trace:
 usbhs_sys_function_pullup+0x10/0x40 [renesas_usbhs] (P)
 usbhsg_pullup+0x4c/0x7c [renesas_usbhs]
 usb_gadget_disconnect_locked+0x48/0xd4
 gadget_unbind_driver+0x44/0x114
 device_remove+0x4c/0x80
 device_release_driver_internal+0x1c8/0x224
 device_release_driver+0x18/0x24
 bus_remove_device+0xcc/0x10c
 device_del+0x14c/0x404
 usb_del_gadget+0x88/0xc0
 usb_del_gadget_udc+0x18/0x30
 usbhs_mod_gadget_remove+0x24/0x44 [renesas_usbhs]
 usbhs_mod_remove+0x20/0x30 [renesas_usbhs]
 usbhs_remove+0x98/0xdc [renesas_usbhs]
 platform_remove+0x20/0x30
 device_remove+0x4c/0x80
 device_release_driver_internal+0x1c8/0x224
 device_driver_detach+0x18/0x24
 unbind_store+0xb4/0xb8
 drv_attr_store+0x24/0x38
 sysfs_kf_write+0x7c/0x94
 kernfs_fop_write_iter+0x128/0x1b8
 vfs_write+0x2ac/0x350
 ksys_write+0x68/0xfc
 __arm64_sys_write+0x1c/0x28
 invoke_syscall+0x48/0x110
 el0_svc_common.constprop.0+0xc0/0xe0
 do_el0_svc+0x1c/0x28
 el0_svc+0x34/0xf0
 el0t_64_sync_handler+0xa0/0xe4
 el0t_64_sync+0x198/0x19c
 Code: 7100003f 1a9f07e1 531c6c22 f9400001 (79400021)
 ---[ end trace [PII_REDACTED] ]---
 note: sh[188] exited with irqs disabled
 note: sh[188] exited with preempt_count 1

The issue occurs because usbhs_sys_function_pullup(), which accesses the IP
registers, is executed after the USBHS clocks have been disabled. The
problem is reproducible on the Renesas RZ/G3S SoC starting with the
addition of module stop in the clock enable/disable APIs. With module stop
functionality enabled, a bus error is expected if a master accesses a
module whose clock has been stopped and module stop activated.

Disable the IP clocks at the end of remove.
References: https://git.kernel.org/stable/c/230b1bc1310edcd5c1b71dcd6b77ccba43139cb5; https://git.kernel.org/stable/c/26838f147aeaa8f820ff799d72815fba5e209bd9; https://git.kernel.org/stable/c/9d86bc8b188a77c8d6f7252280ec2bd24ad6fbc1